Effects of Desiccation on the Rotifer 



TABLE XI 



Efect of temperature. Moisture constant 

 Moist 



249 



TABLE XII 



E^ect of temperature. Moisture constant 

 Dry 



^ Condition of the Life Processes in a Dried Animal 



It has been seen that the causes of injury to Philodina during 

 a process of drying are various in nature. We can distinguish 

 between the mechanical injuries resulting from too rapid desic- 

 cation or from sudden changes in the moisture content of the tis- 

 sues and the injury which is due to slow changes within the body 

 of the animal which continue under the most uniform external 

 conditions. The fact that these changes are greater at high tem- 

 peratures and under conditions of moisture than at low tempera- 

 tures and in the absence of water makes it probable that they are 

 chemical in nature and represent a certain amount of metabolism 

 in the body of the animal. The question naturally arises whether 

 death in the cases cited was due to an actual destruction of the 

 tissues or to some more indirect cause. The former alternative 

 is that adopted by Ritzema Bos in the case of Tylenchus. Many 

 considerations make this view improbable in the case of Philo- 

 dina. In the first place, both old and young individuals may be 

 kept in an apparently healthy condition for at least a week in 

 water free from any organic matter that might serve as food. In 

 this case, where active movements continue all the while and where 



