34 



THE AMEKICAN MONTHLY 



[February, 



The biologist no longer directs his 

 efforts to the discovery of the essen- 

 tial nature of life. He may indulge 

 in fruitless speculations, which, 

 as in the most distant past, still 

 possess a fascination, and lend an un- 

 definable charm to the imagination 

 when it is free to overstep the bounds 

 of finite knowledge and conjure up 

 strange fancies of those mysteries 

 which only an infinite mind can com- 

 prehend. But in his investigations 

 he recognizes a limit beyond which 

 he cannot go. His ultimate aim is 

 not to discover life itself, but to learn 

 as much as possible of its manifesta- 

 tions, and to this end he must become 

 familiar with the primal forms of liv- 

 ing matter from which have grown 

 the living world as we see it now. 



The life-force endows matter with 

 potentiality to pass through a definite 

 series of changes until a certain result 

 is attained, beginning with the sim- 

 plest germ and producing as its highest 

 result, the means of its own renewal 

 through successive generations. 



On the Relationship of ^cidium 



Berheridis, Pers., to Puc- 



cinia Graminis, Pers.* 



BY CHARLES B. PLOWRIGHT. 



There are not many more import- 

 ant questions in the whole range of 

 vegetable physiology, than those con- 

 nected with the Eiitwickelungsgeschi- 

 chte of the fungus which causes the mil- 

 dew in wheat. The magnitude of the 

 issues at stake have been forcibly 

 brought before us who reside in the 

 large corn growing country of Nor- 

 folk, during the last few weeks, where 

 acres of wheat which, within a month 

 or three weeks of harvest gave prom- 

 ise of an abundant yield, were in less 

 than a fortnight blighted to such an 

 extent that in some instances con- 

 siderably less than half a crop only 

 was produced. 



In the month of May of the present 



* Abstract from the paper as published in 

 full in Grevillea. 



year (1881), I performed some expe- 

 riments with the view of convincing 

 myself one way or the other upon the 

 connection said to exist between 

 ^cidium berberidis and Ptcccinia gra- 

 minisj but owing to my non-acquaint- 

 ance with the proper method of per- 

 forming them, they resulted in failure. 

 I then wrote to my esteemed friend, 

 M. Max Cornu, who immediately, in 

 the most kind manner, gave me full 

 and explicit directions as to the prop- 

 er mode of procedure. On the i8th 

 June I commenced a second series 

 of experiments, which have been con- 

 tinuously carried on until the end of 

 September, in which one hundred 

 and seventy-six plants of wheat have 

 been employed. I propose laying be- 

 fore you a detailed account of each 

 experiment, in order that you may 

 be enabled to form your own opin- 

 ion as to their results. But before 

 doing this, I may be allowed to say 

 that they were commenced and con- 

 ducted, as far as it is possible to do 

 so in such cases, with my mind unbi- 

 assed one way or the other, either for 

 or against the theory of heteroecism. 

 For upon the one hand I had a feel- 

 ing that this theory was, to say the 

 least, very remarkable; while upon 

 the other, there was the fact of its ac- 

 ceptance, almost without question, by 

 the majority of continental mycolo- 

 gists, by men whose acumen is un- 

 doubted, and who justly rank in the 

 fore front of scientifiic botany. My 

 mind was in a state of "expectant 

 attention," but I had no other feeling 

 in the matter, having never commit- 

 ted myself to an opinion either /r*? or 

 con. 



Before detailing these experiments, 

 there are some circumstances that 

 have certain weight, both for and 

 against, which should be fairly stated 

 in order that a more just opinion may 

 be formed than would otherwise be 

 the case. In the first place it may be 

 thought that the connection, as differ- 

 ent states of the same fungus, be- 

 tween an yEcidium and a Puccinia is 

 too wonderful to be true. We may 



