SUMMARY OF THE CHAPTER 61 



The study of the action of poisons upon protoplasm gives us 

 an insight into the extreme complexity of the living substance 

 — its composition out of numerous kinds of compounds, many 

 of which are extremely unstable. Not all protoplasm contains 

 the same compounds, hence it must be a very dissimilar thing 

 in different organisms. Not all of the compounds in any pro- 

 toplasmic body are essential to life, for we may act upon a 

 protoplasmic body by a weak reagent, and gradually change 

 its composition so that it will no longer be killed by the strong 

 solution, and all of this without perceptible injury — at least, 

 this is the conclusion to which the study of acclimatization of 

 Protista leads us. The altered chemical constitution will be 

 transmitted in the division of the individual, and tlius the 

 composition of the protoplasm of a race will have been deter- 

 mined by the medium in which it and its ancestors have been 

 living.. 



Finally, we may consider what light the action of reagents 

 throws upon the processes involved in the elementary vital 

 functions. The normal movement of protoplasm is profoundly 

 modified by interfering with the oxygen supply. Thus, when 

 the oxygen pressure is diminished, movements are retarded ; in 

 the presence of pure oxygen they are accelerated. Some anees- 

 thetic or paralj^zing agents — e.g. chloroform and some alka- 

 loids, veratrin, atropin, co'caine, strychnin, and antipyrin — give 

 rise first to acceleration, then to disappearance of movements 

 in the protoplasm. Protoplasmic movement is, consequently, 

 closely associated with oxidation, and it does not occur in the 

 absence of irritability. 



Normal locomotion is interfered with by strychnin and co- 

 caine. Their stimulating action produces accelerated move- 

 ments, and these are accompanied by loss of coordination. 



Since many catalytic poisons (anaesthetics) destroy irrita- 

 bility, one may conclude from the action of these chemical 

 agents that (p. 7) stability of molecular movement is essential 

 to the performance of this function. 



Disturbance of the excretory function results from the action 

 of CO, NHg, chloroform, cocaine, strychnin; at least, an ex- 

 cessive vacuolation of the protoplasmic body occurs under the 

 action of these agents. 



