Effects of Desiccation on the Rotifer 215 



presented by both sides in the form of experiments occupied several 

 months and the final report of the commission presented in March, 

 i860, covers a hundred and forty printed pages. This report 

 on the whole sustains the contentions of Doyere, not because of 

 any inaccuracies in Pouchet's results, but because they are largely 

 negative in nature while Doyere's are positive. It concludes 

 with the words, "des animaux * * * amenes au degre de dessic- 

 cation le plus complet qu'on puisse realiser dans I'etat actuel de la 

 science, peuvent conserver encore la propriete de se ranimer au 

 contact de I'eau. " Although the language employed in the report 

 is rather guarded, it evidently was the opinion of the commission 

 that life under these conditions could exist only in potentia. 



The results obtained by this commission as well as those of 

 Doyere and Spallanzani are contradicted by the observations of 

 some of the more recent workers on the subject. In 1873 H. 

 Davis, a member of the Royal Microscopical Society and a student 

 of rotifers published a paper which has since been largely quoted 

 and in which he stated his conclusions that in Philodina, at least, 

 the desiccation when followed by revival is only an apparent one, 

 the animal being able to protect itself by means of a gelatinous 

 secretion against the loss of its body fluids. He demonstrated 

 how such a secretion could be effective by showing that grapes 

 covered with a thin coating of gelatine remained in a juicy condi- 

 tion for a long time even in the vacuum of an air pump while grapes 

 not thus treated soon lost their water and assumed a shriveled 

 appearance. The fact that rotifers dried with a small quantity 

 of sand are capable of recovery even after a prolonged exposure 

 to extreme conditions while those dried on a clean slide for a much 

 shorter time are not, had always been more or less puzzling to 

 naturalists since it was first observed by Spallanzani. It received 

 a ready explanation on Davis' theory, it being assumed that in 

 the former case where drying was slow the animal had time to 

 protect itself by pouring out a secretion, while in the latter case 

 drying was so rapid that the animal, not being able to form its 

 usual protection, w^s killed. This explanation was so simple and 

 so in accord with the facts known for other animals that it was 

 irr?1fnediately accepted by many and at the present day is still 

 frequently quoted. 



