Effects of Desiccation on the Rotifer 235 



change which causes it to resist the coagulating effect of high tem- 

 peratures while still retaining its water ? Such a supposition is on 

 its very face highly improbable. On the other hand if we believe 

 that there is an actual loss of water these facts fall in hne with the 

 observations of Lewith and others that in egg albumin with loss 

 of water the coagulation temperature rises from 56° to 145° C. 

 There is every reason to beheve, therefore, that in Philodina we 

 have to do with a true desiccation of the body. This is shown by 

 the chemical and physical tests mentioned above, by the great 

 amount of shrinkage that occurs at the time of drying, by the fact 

 that the cuticle is freely permeable to gases and to water vapor, 

 and by the additional fact that coagulation is not caused by rela- 

 tively high temperatures. Furthermore, it has been shown that 

 the only plausible explanation that has ever been given of a method 

 by which loss of water could be prevented is based on insufficient 

 observation and is not borne out by the facts. We must not as- 

 sume, however, as many have done, that the desiccation is ever 

 an absolute one. Even with the most perfect desiccating devices 

 known it is impossible to remove the last traces of water at ordi- 

 nary temperatures. The chemist recognizes the fact that in 

 organic analysis it is necessary to heat the substance which is 

 being analyzed almost to the charring point to remove all of the 

 water it contains. With rotifers this is impossible since long be- 

 fore this point is reached certain irreversible changes have occurred 

 which cause the death of the animal. It is certain that no rotifer 

 has ever hved after an absolute desiccation. It is useless, there- 

 fore, to speculate whether or not life would be possible after com- 

 plete removal of water, since such a condition cannot be attained 

 by the means in our possession without destroying the very struc- 

 tures on which life depends. But the fact that an animal with no 

 means of protecting itself against loss of water save the hygro- 

 scopicity of its tissues may remain capable of resuming its normal 

 vital activities after a sojourn of weeks or even months in a vacuum 

 or a desiccator is in itself a striking one and one which must neces- 

 sarily enlarge our conceptions of the properties of Hving matter. ' 



