Livingston : Chemical stimulation of a green alga 27 



This author observed no acceleration in reproductive activity. 

 The accelerations which he noted, — and they occurred for algae 

 with all salts excepting AgCL, and CuS0 4 , and with all salts tried 

 for fungi, — always consisted in a hastening of the growth rate, thus 

 giving weight of yield greater than that of the control. His form of 

 Stigeoclo)iiuui was different from mine. Nothing is said about its 

 being polymorphic, while with my form the important responses 

 are all those which are bound up in the physiology of polymorph- 

 ism. This difference in the response of acceleration would seem 

 to indicate that even the most nearly related organisms may react 

 differently towards the same stimuli. The concentration limits 

 were not determined sharply enough to make any rigid comparison 

 of these profitable. As far as comparison can be made the results 

 of my experiments seem to agree in a general way with those 

 obtained by Ono. 



Richter * was unable to get an acceleration of growth in Asper- 

 gillus with Cu although he obtained this response with Zn. It 

 may be that in these lower forms there are great physiological 

 variations within a single species. This would account for some 

 of the apparent discrepancy in regard to the effects of these salts 

 which have been tried so often. For a description of the behavior 

 of a form of Penicillium peculiarly resistant to copper and one 

 extraordinarily resistant to arsenic, see the work of De Seynes f 

 and Gosio4 



Stevens § tested the influence of a number of salts in inhibiting 

 the germination of spores of several fungi. The following table 

 compiled from one of his, gives the lowest inhibiting concentrations 

 for the forms there named, with respect to those salts which he 

 and I have both tested. I have corrected his terminology from 

 11 to m, and have added underneath his figures the approximately 

 equivalent concentration in the normal and decimal system. The 

 sign > preceding a concentration denotes that the limit as stated 

 is somewhat too low. 



* Richter, A. Zur Frage der chemischen Reizmittel. Centralbl. fiir Bacteriol. 7 : 

 417-429. 1901. 



|De Seynes, J. Resultats de la culture du Penicillium cupricum Trabut. Bull. 

 Soc. Bot. France 42 : 451-455, 482-485. 1895. 



J Gosio, B. Zur Frage wodurch die Giftigkeit arsenhaltiger Tapeten bedingt 

 wird. Ber. Deutsch. Chein. Ges. 30 : 1024-1026. 1897. 



\ Stevens, F. L. The effect of aqueous solutions upon the germination of fungus 

 spores. Bot. Gaz. 26 : 377-406. 1898. 



