[Title fragment 1.1] [Title fragment 1.2] [Title fragment 1.3]
[Title fragment 2.1] [Title fragment 2.2] [Title fragment 2.3]
[Title fragment 3.1] [Title fragment 3.2] [Title fragment 3.3]


Let's go back to the year 1834. Just at the moment we have received a new issue of the magazine  Isis by Oken , volume 1834, with a thrilling article featuring the water bear Macrobiotus hufelandi  .
We are quite lucky to have such a nice article which can be read and understood by amateurs, too.
Several decades will have to pass until to the foundation of microscope amateur magazines like the Quekett Microscopical Club Journal Magazine (1868) or the German MIKROKOSMOS (1907). And it will take a further century from this point until to the foundation of our much more shallow illustrated product, the Water Bear web base with its  Still Image Gallery I .
So, when just sitting there at our desk in 1834, we are really lucky to enjoy the extensive text and the crisp woodcuts in the magazine Isis by Oken . When our fingers touch the paper we feel that this product will persist even in slightly moist and dusty public libraries for centuries.
But let's concentrate on the text now, a text which still today is considered as the first scientific description of the tardigrade Macrobiotus hufelandi , moreover it is a good example of an early controversial scientific discussion and the human psychology behind:

Sixth Meeting, September 24th.
... the next speaker  Otto  presented a text by the honourable Schultze from Greifswald referring to an organism called Macrobiotus Hufelandii. As additional material Otto presented a drawing and a small package of sand and dry material, the habitat of the animal unter consideration. See table XIV.

[Blick in Okens Isis]

Detail of tab. XIV
taken from the magazine
Isis by Oken (1834)

The text by Schultze is as follows:
"The Macrobiotus belongs to a group of strange little animals which can survive in completely dry state for a long time, even several years, and can revive just by means of a bit of moisture. The Macrobiotus is the biggest and most perfect member of this remarkable group. Same as   Furcularia rediviva Lam.   and  Vibrio Anguillula, which have this property in even more elaborate form, the Macrobiotus can be found among grains of sand and within the moss cushions in gutters and on roofing tiles but seems to be more rare than those other organisms.
I think that the Macrobiotus has been observed already by the hardworking Spallanzani and has been mentioned in his  Opuscules de physique animale et végétale  traduits par J. Senebier, Tom. II. Genève 1777. pag. 346, here called le tardigrade , though Spallanzanis illustrations, copied here as tab. IV. fig 7 und 8. und tab. V. fig. are far from being perfect. But they may be used for comparison with my own drawings which I will describe here now:

fig. 5 fig. 6 fig. 7

Comment: starting from this point Schultze refers to his own drawings.

fig. 1

fig 1. is the respective animal, as seen from top, with a linear maginification of 270.
a. the bare mouth opening which is followed by a long buccal tube b.
c. are two thin bone structures which move during the process of chewing;
d.d. is the egg-shaped chewing muscle, which surrounds the teeth;
e. three teeth on each side;
f. the short oesophagus;
g.g. two gland-like organs, perhaps salivary glands;
h. the stomach or intestine, there seems to be no sharp disctinction possible between those two;
i. the anus;
k. the simple ovary, filled with eggs;
l. a simple kind of central blood stream;
m.m. two lateral streams;
n. a crosslink between those streams in which we can perceive the most intensive movement of blood globules;
o. die Augen.

The animal has feet each of which are armoured with 4 claws;

fig. 4

fig. 4. represents the first pair of feet as seen from below, with a linear magnification of 400.

fig. 2

fig. 2. The Macrobiotus, contracted after the evaporation of the water.

fig. 3

fig. 3. The same after complete desiccation, with the skin folded to wrinkles.
b.c. are sand grains, between which the animal a.a. has been dried.

When revived by means of destilled water or rain water not all of them come back to active life. Often they remain dead, in particular when being dried alone on a glass surface; nevertheless even some of those have been perfectly revived and I have observed that they were able to deposit eggs from which youngsters emerged within three weeks.

The animal belongs to the crustaceae und should be characterized as follows:

Macrobiotus: Corpus elongatum, depresso cylindricum, in decem segmenta distinctum. Pedes octo, alternis segmentis a quarto ad decimum affixi. Caput antennis destitutum, oculi duo.
M. Hufelandii: Corpore minimo 1/24'''- 1/3''' longo, flavo cinereo, pedibus quadrangulatis.

For those among the gentlemen of the audience who want to check the revival ability of the animals, similar as with Vibrio and Furcularia, I have added a small package of sand and dry material, which has been kept in dry state since May 2nd, 1829. A small quantity of the material, about the volume of two pin heads has to be flooded with a drop of destilled water and then can be investigated under the microscope; it will then be possible to follow the process of swelling and shape variation until to first crawling movements and in the end, swimming away."

Comment: no wonder that the conservative scientific authorities were slighty jealous and suspiciously followed this smart demonstration by Schultze. As a consequence the authorities presented a counter argument in the same issue of Isis by Oken . Even today we understand that this comment had to be longer than the original report ;-)

The editors have the honour to quote from a letter by Prof. Ehrenberg the following highly interesting notes commenting on the previous report: "Prof. Retzius from Stockholm brought along from Breslau a portion of the gutter sand which had been distributed by Professor Schultze from Greifswald at the scientists' meeting with the claim that the phenomenon of the revival of dried rotifers might be observed by means of the sample. One of the animals revived by water is being called Furcularia rediviva by Mr Prof. Schultze, and the other Macrobiotus Hufelandii. He considers them as two yet unknown species. The fact, as resented by Mr Prof. Schultze, though well known since along time, is being interpretated in a way which is new for me and should be checked with thanks by all scientists. Nevertheless the two individuals were not at all new for me. What was called Furcaria rediviva apparently are two species of my genus Philodina; they are to be considered as Philodina erythrophthalma, which I have shown in my first paper about small volume structures and Philodina roseola which I have characterized in the second paper and the intestine of which I have shown as well in this publication. By the way the Furcularia rediviva by Lamarck to which the author seems to refer, as can be seen from Müllers drawing even is a species of another genus, which in my opinion has to be regarded as Rotifer vulgaris. As far as the second animal is concerned, I have not been able to find it in the sand sample. But I suspect from the description of Mr Retzius and Mr Carus both of whom have been present at the demonstration that it also shows an animal already known to me. When I showed my drawings to them they agreed that it was the same as mine. I have held a lecture last year for the local Society of Naturalists which featured the bizarre evolution of a new animal. This is in preparation for print in "Schriften". I called the respective animal Trionychicum ursinum, it is of a maggot-like, long shape. It has 8 plump feet, each of which equipped with 3 claws and a short conical proboscis with two inner jaw parts or teeth on a thick, spherical throat. The thick, simple intestine with a long and thin oesophagus which I had had filled with colorants is very similar to those of the rotifers (Hydatina), but the two stomach glands are and the rotifer organs are missing, whereas it has two considerable black eyes in the center of the head (possibly neck eyes). The most strange fact is that it deposits its big eggs in its own skin during moulting, and as a consequence takes along a simple thick bag with eggs on its way (similar to a cyclops). One can see the shapes of 4 to 6 or eight legs and claws at the egg bag. The youngsters are able to find their way out of the eggshell themselves and have eight feet as well, in fact they look very similar as the adults. I was not able to identify males and females and I do not know the anatomy of the various systems within this organism. This strange animal, living freely in mud, seems to be related to the Lerneae where I would place it within the system of animals until further evidence will help to classify it more safely. The actual typical length is 1/6 line, sometimes 1/4'''. The size of the eggs is 1/36''', the length of the youngsters 1/24''', so a size range between 1/24 ''' and 1/4''' has to be noted. It is now up to Mr Prof. Schultze to check whether the Macrobiotus described by him is the same animal as already described by me, as it is important to identify any synonyms. The animal observed by me is unable to swim.
As this report has not convinced me that desiccated animals of no matter what species might revive after death I will try to encourage further investigations of this interesting topic and at the same time would like to add some of my own results. As Prof. Retzius urged me to publish a comment I would like to ask the editors to place my comment close to the original reports when it will be printed.
Numerous experiments which I have made with resprect to the revival of thoroughly dried infusoria never yielded a positive result. The species investigated by me were: Rotifer vulgaris, Philodina erythrophthalma, Hydatina senta, Brachionus urceolaris, Euglena sanguinea, Euglena viridis, Monas pulvisculus, moreover Anguillula fluviatilis, which I do no more consider to be a member of the infusoria group. I still do have big amounts of dried microorganisms from earlier experiments. I have made casual observations of almost all rotifers investigated by me. The carefully planned experiments, not on mass samples but on individual animals never revealed any miracles. I have learnt by isolation and by direct investigation of individual rotifers that they have a rather long life as I have reported already elsewhere. Single rotifer individuals of any species which were dried on a slide revived seldom after two hours never after 12 or more hours, most many of them ended as fragments. In combination with plant detritus by which they were surrounded, in particular between Oscillatoria I have seen rotifer organ movements of rotifer species in the strict sense and Philodinas, but never encountered this with Hadytina, Brachionus, Euglena or Monas. From this I concluded that those more muscular species had not been dead. After a fortnight I had recorded no return to movement though I think that in an environment protected from desiccation a slower vital activity might be maintained for one month or more. According to Mr professor Schultze's claim the sand sample with the dried animals was more than three years old. So I was very eager to learn which factor might have supported and preserved the vital functions in this case. I noticed immediately that all those Philodina coming back to active life had not an empty stomach but an intestine filled with green particles. I looked for the source of those green particles in the sample and found many fine well-preserved threads the shape of which resembled those particles which I had found in the intestine of the rotifes. Moreover I have seen eggs deposited freely close to the animals and animals of very different size.

Comment: please note that Ehrenberg now goes over to sudden attack.

As I do not believe in marvels beyond those step-by-step processes which can be observed in nature I would like to explain the interesting reports about the revival of rotifers which were kept dry for more than three years as follows:
The revival seems to be a deception. The rotifers were neither dead nor benumbed, they didn't even live for such a long time. Those animals which had contracted to a kind of egg-shape when surrounded by a slimy not completely dry environment might continue to take food for some time as they are still able to eat with their jaws protruding from the laterally situated mouth. From my early experiments moreover has to be concluded that poor nutrition tends to prolong the lifetime of the animals and to slow down the reproduction. It seems to be much more realistic not to believe in miracles but to assume that those animals continue feeding and egg deposition as long as they are surrounded by a slightly wet, viscous medium which is sufficient to preserve minimum internal humidity and nutrition. Because of this the seemingly revived animals were not those that dried three years ago, but their great-grandsons. Many larvae of insects live in seemingly dry media but still have some kind of local wetness around them. As those rotifers seemingly dried for three year came back to perfect movement and coordinated use of limbs within half an hour it must be assumed that they never had completely lost this ability but were only a bit restricted. It is no contradiction when those freshly wetted animal concretions show no trace of movement in the first moment, as active Philodina and Rotifera, when being disturbed, contract to a spherical shape and often maintain this state without interior or exterior movement for half an hour. The sudden excess of the long-awaited water might be irritating at first and it might take some time until the animal can make use of the regained liquid element."

In spite of his long comment the famous and respected professor Ehrenberg was wrong. Today we know that Prof. Schultze's view of the experiment was correct: in fact the tardigrades are able to slow down their live activity very close to zero and can survive poor environmental conditions in dry state for at least several years. So the revived animals are not the 'great-grandsons' of the animals as Ehrenberg assumed but exactly those individuals that had been dried a few years before.
In the next issue of the Water Bear web base we will have a look at a series of photographs which documents how a completely dry and seemingly dead water bear comes back to active life again within 15 minutes, just by means of a small droplet of water, exactly as described by professor Schultze already in the year 1834.


Isis von Oken, vol. 1834, text row 709 to 713 and table XIV

Comment: please keep in mind that the translation from ancient German to modern Englisch has not been easy and that I cannot guarantee for the correct flavour of each minor detail though I have done my best. In case you should be able to understand the German original you might as well look at the German version at  http://www.baertierchen.de/dezember.html.
It might be slightly confusing to read Schultze's description of a 'blood stream' whereas modern authors confirm that tardigrades have neither blood nor a circulation system. But in fact there is some kind of circulating liquid medium within the water bear body cavity which is very similar in function to blood and circulation. So this discrepancy seems to be not so much a question of different facts but of different definitions of the terms 'blood' and 'circulation'.


© Text, images, and video clips by  Martin Mach  (webmaster@baertierchen.de).
Water Bear web base is a licensed and revised version of the German language monthly magazine  Bärtierchen-Journal . Style and grammar amendments by native speakers are warmly welcomed.

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