2] DESICCATION AND PROTOPLASMIC FUNCTIONS 61 



sometimes been regarded as death. By PREYER ('91) it has 

 been called "anabiosis." I shall call it desiccation-rigor, and 

 correlate it with phenomena, produced by various other agents, 

 which cause the cessation of a movement that is restored again 

 when the action of the untoward agent is withdrawn. 



And these are just the conditions we meet with here, ces- 

 sation of activity without loss of power of revival. This was 

 very evident from the work of SPALLANZANI (1787, Tom. II, 

 pp. 212, 213). This author showed clearly that one and the same 

 adult rotifer can be observed in the evaporating drop, until all 

 the water is gone, and it has lost all movement and its normal 

 form. If, after an hour, the slide is moistened again, the 

 rotifer reassumes, by degrees, its natural form and activities. 

 SPALLANZANI noticed, what has been the nearly unanimous 

 testimony of subsequent observers, that a rotifer dried for 

 hours on clean glass does not revive ; revivification occurs 

 only when the rotifers have crawled into sand. As for the 

 length of time during which desiccation-rigor may persist 

 in rotifers without death occurring, we know only that it may 

 be considerable, extending through months, and even years. 



Similar phenomena to those observed in rotifers have been 

 described for tardigrades and certain nematodes, although these 

 organisms have not been studied in so much detail. Among 

 the tardigrades only those species which live in moss, and 

 are thus especially liable to desiccation, withstand drying. 

 (LANCE, '94.) Among nematodes, Tylenchus devastatrix, 

 KtJHN, which lives in grains of wheat, is a classic object of 

 study. Strongylus rufescens is, according to RAILLIET ('92), 

 capable of resisting dryness for 68 days or more. We may 

 thus conclude that adult organisms of certain species may be 

 subjected to desiccating influences, and that those same indi- 

 viduals may resist them so as to reexhibit activities after the 

 return of favorable conditions.* 



While the results of these drying experiments are scarcely 

 doubted, much difference of opinion has arisen concerning the 

 interpretation of the results. The first moot point is the 

 degree of desiccation which the protoplasm of the organisms 



* See in connection with this the valuable report of BROCA ('61). 



