248 



Merkel Henry 'Jacobs 



%■ 



TABLE X 



Efect of moisture. Temperature constant (40°) 



It is seen from the tables that those kept in the moist atmosphere 

 showed a far higher mortahty than the others. The percentage 

 that recovered was only 38 per cent as against 85 per cent at room 

 temperature and o per cent against 71 per cent at 40°. We are 

 forced to conclude therefore that death is not due to loss of water 

 but to some process that is promoted by the presence of water. 

 This being the case, what becomes of the view of Davis and others 

 that rotifers protected from desiccation live while those exposed to 

 it die .? If a rotifer be protected by a waterproof and airtight 

 cyst and be moist inside anyway, why should the presence of a 

 little moisture in. the air surrounding it be so injurious.^ This 

 and other similar experiments show how untenable such a theory is 



/ Effect of Temperature on Mortahty 



It has been seen that rotifers dried at a high temperature show a 

 lower mortality than those dried at a low one. If, however, the 

 high temperature be allowed to continue for any length of time 

 it has a harmful effect. This relation suggests that certain meta- 

 bolic changes may be a source of injury to the animals since chem- 

 ical reactions in general, including those which go on in the bodies 

 of living organisms, take place far more rapidly at high than at 

 low temperatures. The fact that the moisture causes an increase 

 in the mortality, the greatest number of deaths occurring at the 

 high temperature in the moist atmosphere, confirms this view. 

 For convenience in comparison the two preceding tables are re- 

 arranged so as to make the amount of moisture the constant factor, 

 the temperature being the variable one. 



