§2] EFFECT ON STRUCTURE AND FUNCTIONS 77 



water flagellate Anisonema acinus, Butschli, is cultivated for 

 many generations in water to which sea salt is gradually added, 

 its structure is modified with the increasing density. The in- 

 dividuals become smaller and their feeding canal is not well- 

 formed. Another change, which has been studied only in 

 Vertebrates, is loss of weight. Bert ('71) found that a gold- 

 fish plunged into sea water loses 67% of its weight, and that 

 young eels lose 10% to 17%. This fact also is clearly what 

 we should expect from the theory of action of solutions, accord- 

 ing to which the weak solutions of the body cavity should lose 

 water. Thus, the changes produced in the structure of proto- 

 plasm by more or less dense solutions are chiefly the results of 

 osmosis. 



b. Among the functions of protoplasm, general movements 

 (with locomotion) and excretion seem to be most markedly 

 affected by density. Thus, Kuhne ('64, p. 48) found that, when 

 first subjected to a 1% NaCl solution, the movements of Amoeba 

 became niore lively for a moment. Engelmann ('68, p. 343) 

 noticed the same acceleration in movement in the cilia of the 

 epithelium lining the frog's oesophagus when subjected to pure 

 water — hence, to a weaker solution than the normal cell fluid. 

 Even after death, fresh water causes a transitory activity in 

 the cilia. In all cases, after a minute or two (1% solution) the 

 movements begin to diminish, until at last they cease. This 

 cessation of movement, whether due to loss or imbibition of 

 water, is not necessarily death. For, if the abnormal con- 

 centration has not acted for too long a time, the movements 

 return when the protoplasm is placed again in its normal fluid. 

 (KtJHNB, '64, p. 48; Engelmann, '68, p. 343.)* At a certain 



* A similar cessation of movement occurs wlien the lower organisms are sub- 

 jected in water to very great pressures. Experiments upon tliis phenomenon 

 have been made chiefly by Regnard ('84, '84'!-'84'i, and '86), Cektes ('84, 

 '84"), and Roger ('95). Eegnard was able, by the use of a special apparatus, 

 to subject beer yeast, in water, during 1 hour, to a pressure of 1000 atmospheres 

 (about 1000 kilograms per sq. cm.). When yeast so subjected was then placed in 

 sugared water, it showed at first no activity. It was not dead, however, but had 

 fallen into a latent life ; for 1 hour after it had been relieved from pressure it 

 revived and fermentation set in. Some algae, Infusoria, and aotinians, subjected 

 to 600 atmospheres during 10 to 60 minutes, or to 300 atmospheres for 24 hours 

 (Ceetes, '84), exhibited a similar temporary rigor. Likewise muscle at 200 to 



