34 



ANDREWS. 



perature or state of the water which had caused death to the 

 adult mass as such, seeming for these innocuous. Where 

 death was escaped by the adult through formation of mac- 

 rospores, these reorganizations of the adult mass showed an 

 indifference to adverse conditions which was in many cases 

 remarkable. I have seen Protozoa spores swim actively for 

 many minutes in strong solutions of poison, such as corrosive 

 sublimate, and to resist for some moments ammonia, the 

 faintest trace of which actually disintegrated the adult. 



These facts may go to explain partially the extraordinary 

 resistance of bacteria and their spores to action of heat, cold, 

 and other states inimical to the living substance. 



The prevalence of ^g^ membranes and of ectosarc-like areas 

 in embryonic states of Metazoan substance also receive here 

 some light. 



[29] It was found that to shake starfish or echinus eggs, in 

 early stages, not too hard, was productive of perceptibly greater 

 resistance to reagents, to shaking and also to pressure ; in other 

 words, the viscosity of the mass, or most likely of the peripheral 

 portion, was increased by such treatment. The same result was 

 had from pressure, not strong enough to rupture, between cover 

 and slide. The substance here opposes an adverse environ- 

 mental condition by a physical change of state. In this con- 

 nection there are facts obtained in the study of contraction 

 phenomena which are of vital importance. The reader is most 

 particularly referred to the phenomena of cell-connection, both 

 as seen in mechanical experiment and in the natural course of 

 events.^ 



An excellent instance of rhythmic variation of viscosity is 

 had in the pellicular membrane which forms the wall of the 

 contractile vacuole of amoebae. This was found, contrary to 

 the most widely accepted belief, to be not a stable, or per- 

 sistent, substance structure. The subjects of observation were 

 A. proteus and A. radiosa. 



At times in its rhythm, though not in each recurrence of 

 this, the vacuole disappears ; not merely optically, but actually. 

 For during collapse, which at some times seems to be more 



1 See Activities; — rhythms of viscosity. 



