24 Livingston : Chemical stimulation of a green alga 



j. The response in phenomena of reproduction. — With most of 

 the cations studied there is a curious difference between the effect 

 of drying solutions (of high pressure) and poisoned ones. This lies 

 in the observed fact that in the latter zoospore production may 

 not only be as active as in the unpoisoned control, but that it may 

 be much more active, while in the former zoospore production is 

 entirely inhibited. Thus extraction of water produces the palmella 

 form and inhibits zoospores, while the presence of toxic cations 

 produces the palmella form, but also, at some concentration, gen- 

 erally accelerates the production of zoospores. This would seem 

 to prove that the relation between the two sets of responses is not 

 as simple as might otherwise be supposed. It seems possible 

 that the production of zoospores is due to a somewhat different 

 set of changes in the protoplasm from those involved in ordinary 

 growth, a set of changes which may be started by several appar- 

 ently different external factors. The phenomena of reproduction 

 lie at present so much within the province of the unknown that it 

 would probably be unprofitable to attempt any hypothesis in this 

 regard. Attention may be called here, however, to the fact that 

 there are fairly well-known activities taking place simultaneously 

 within plant protoplasm, and yet controlled by entirely different 

 sets of factors. As examples may be mentioned the processes of 

 photosynthesis and respiration. 



The fact that the acceleration here held in view is not observed 

 in case of the cations, K, Rb, and Na, and is somewhat question- 

 able in that of Li and Mg, together with the fact that these ele- 

 ments are among the least toxic, seems to show that there is some 

 sort of a relation between the responses of death and change in 

 growth, on the one hand, and of reproduction on the other. This 

 matter of stimulation of reproductive activity may be a fertile field 

 for further investigation. 



Lillie, R. S. Relation of ions to ciliary movement. Am. Jour. Physiol. 10 : 

 419-443. 1904. 



Mathews, A. I'. The nature of chemical and electrical stimulation. I. The 

 physiological action of ions depends on electrical state and electrical stability. Am. 

 Jour. Physiol. 11 : 445-496. 1904. 



Cole, S. W. Contributions to our knowledge of enzyme action. I. Influence of 

 electrolytes on action of amylolytic ferments. Jour. Physiol. 30 : 202-220. 1903. — 

 Contributions to our knowledge of enzyme action. II. Influence of electrolytes on 

 the action of invertin. Jour. Physiol. 30 : 281-289. 1903. 



