58 PETER SCHMIDT 



question was studied in a more detailed way by Gavarret ('59). 

 In 1860 the 'Societe de Biologic' in Paris was in such a degree 

 interested in clearing up'this question that it elected a special 

 commission, with Broca as president and Balbiani, Brown- 

 Sequard, Darest, Guilliemint, and Robin as members, for con- 

 trolling the experiments on revivification of Rotatoria and 

 Tardigrada. This commission (Broca, '60) not only confirmed . 

 the fact of the reviving of these microscopic animals, but also 

 stated their excessive endurance to high temperature. In the 

 dried state they endure a temperature of 100°C. and can remain 

 for very long time in a vacuum without loss of vitality. 



However, this question has not been reviewed and reexplored 

 in full measure by modern methods. Some zoologists who have 

 studied the resuscitation of one or another respresentative of 

 Rotatoria and Tardigrada for instance, Fromantel ('77), Plate 

 ('86), Zacharias ('86) came to negative results, but the others, 

 such as Schulz ('15), have not only confirmed the results of 

 previous authors, but have also given new proofs of the re- 

 sistance of exsiccated animals to the absence of oxygen. Ac- 

 cording to experiments of Schulz, the Tardigrada, Rotatoria, 

 and Nematodes can remain exsiccated during one year in an 

 atmosphere of pure hydrogen and not lose their vitality. 



Summarizing all that is known upon this subject, one may say 

 that most experimenters have succeeded in the revivification of 

 exsiccated Tardigrada, Rotatoria, and Nematodes, which, living 

 in moss and sand, are adapted to such loss of water. The body 

 of these microscopic animals wrinkles up completely by the 

 exsiccation and loses its form, but if placed afterwards in water it 

 swells and regains its natural size and contour. It can be re- 

 garded as proved, also, that such exsiccated animalcules endure 

 easily and without injury high temperatures (100°C. and more; 

 in experiments of Doyere, 140°C.), as well as absence of oxygen. 



But many points of this remarkable phenomenon remain 

 unelucidated and require further investigation. Firstly, it 

 would be necessary to ascertain how far the exsiccation can go 

 without loss of vitality. It is, a priori, iihprobable that the 

 animalcules can lose all the water contained in their living tissues, 



