4o8 Pedigreed Race of Parainwcium [Mar. 



tures. The same point is illustrated by some previously published 

 experiments with the salts of potassium in which it was found that 

 the dibasic potassium phosphate caused an acceleration of the rate of 

 division during one part and a retardation of the rate during another 

 part of the life of the culture. 



The data show that organisms which have been subjected for 

 long periods to small amounts of alcohol, and which have attained 

 a greater number of generations than the non-alcohol series, are 

 more susceptible to copper sulphate ; and that the organisms which 

 have been subjected to the greater strength are more susceptible to 

 copper sulphate than those subjected to the less strength. This 

 shows clearly that alcohol, in the small amounts which may be said 

 to be " beneficial " from the Standpoint of metabolism, since more 

 cell divisions have occurred, definitely renders the cells more sus- 

 ceptible to the " injurious " effects of copper sulphate. In what 

 way this is brought about is not evident from the results secured to 

 date. It seems improbable that we are justified in assuming that 

 the alcohol has brought about a general "lowering of resistance," 

 in view of the fact that the general effect of the alcohol is to in- 

 crease cell division. The results suggest that probably alcohol 

 effects some change in the permeability of the cell membrane to 

 copper sulphate. 



VII 



Evidence from many sources points to the conclusion that excre- 

 tion products, in the case of many organisms, have a profound 

 effect on cell division and growth, and also that the Infusoria, 

 under favorable conditions of food and temperature, excrete con- 

 siderable amounts of carbon dioxide, together with various other 

 end-products of metabolism, which may reasonably be expected to be 

 evident through biological as well as chemical tests. 



The ordinary hay Infusion, teeming with animal and plant life, 

 is a microcosm in which every organism may, and probably does, 

 in some degree affect the well-being of every other organism 

 present. Besides the obvious influence exerted by animals in feed- 

 ing on other forms and by green plants through photosynthetic 

 processes, one would expect the effects of organisms on their envi- 

 ronment by the elimination of products of their metabolism or 



