48 ARTHUR W. GREELY. 



testimony to the conclusion already reached by Braem and others, 

 that in resting stages of this sort, development can commence 

 only after some physical change has occurred in the proto- 

 plasm through the action of a low temperature or other changes 

 in the external conditions. These experiments further seem to 

 show that the changes produced in the protoplasm by lowering 

 the temperature are identical with those produced by an extrac- 

 tion of water, as has already been indicated in the experiments 

 on Protozoa. 



It is interesting to note that the same forms of stimuli (/. e., a 

 lowering of the temperature and an extraction of water), which 

 hasten the development of the moth, also produce artificial par- 

 thenogenesis "of the starfish egg. This fact lends weight to the 

 idea, expressed by Loeb, that artificial parthenogenesis consists 

 merely in the acceleration of developmental processes already 

 present in the egg. 



III. EFFECT OF TEMPERATURE ON THE ABSORPTION 

 OF WATER BY MUSCLE. 



If the conclusion drawn from these earlier experiments, that a 

 reduction of the temperature produces changes in the protoplasm 

 that cause it to lose water is true, then variations in the tem- 

 perature ought to have a decided effect on the absorption of 

 water by muscle or other animal tissue. The experiments of 

 Loeb 1 and Webster 2 on the gastrocnemius of the frog have 

 demonstrated that this muscle always behaves in a very constant 

 way, as far as can be determined by its change in weight, toward 

 each salt solution in which it is immersed. In some salt solu- 

 tions the muscle always absorbs a definite amount of water at the 

 normal temperature, in others of the same osmotic pressure it 

 always loses a definite amount. The only variation in this be- 

 havior of the muscle toward salt solutions occurs with the change 

 of seasons, the muscle of winter frogs differing widely from 

 summer frogs in this respect. This fact had been the only indi- 

 cation that temperature in any way affected the absorption of 

 water by the frog's muscle, and the influence of the temperature 



1 Loeb, Archiv. f. d. ges. Physiol., 1899, LXXV., p. 303. 



2 Webster, Univ. of Chicago Decennial Publications, 1902, X., p. 105. 



