No. 643] 



ORTHOGENESIS IN BACTERIA 



115 



of regard for your time and patience, I have merely pre- 

 sented in outline each of the important considerations 

 which I deem of direct significance to tlie question at 

 issue. I have presented tlic difHciiltio wliicli lie in the 

 path of treating- l)acteria t'vom tlic point of view of 

 orthogenesis, and yet liave shown that tliey may l)e so 

 treated with certain justitiahle assumptions as a hasis. 

 Having thus treated them, however, I have shown that 

 whether the theory of orthogenesis holds for hacteria or 

 not, it can not be considered as explaining anything, but 

 merely as a mode of describing our observations. I have 

 gone into the more fascinating and what seems to me to 

 be the more useful discussion of the origins of living 

 cells and the position of the bacteria with regard to such 

 primordial cells. I have mentioned the various hypoth- 

 eses which, in my opinion, may be considered to be the 

 most plausible in that connection, and liave sliown tlie 

 weaknesses and the strength of eacli. Tt Im- lu'vu my 

 purpose to give an unbiased presentation of ni.\- own 

 hypotheses and those of others witlu^nt picjndict' to anv 

 so that you might be enabled to dis('n>s tlicni all and 

 arrive at your own conclusions. AVitliont a tlioroniili 

 review of the literature of bacterial i)liysi()louy and mor- 

 phology, it is not easy to obtain a broad enougli view of 

 the subject to do it justice and I would urge particularly 

 that those who are interested in it acquaint themselves 

 with the absorbing and inspiring literature of the subject 

 of mutation in microorganisms. I believe that it is full 

 of significance for biological progress and I wish tliat cir- 

 cumstances made it possible for me to ))re>ent a brief 

 review of it for your consideration. As it is, I must 

 content myself with directing your attention to it and with 

 expressing the hope that my humble efforts in preparing 

 and presenting this paper will constitute a ste]) forward 

 in our progress of thought and expcrinn-ntation on ])rob- 

 lems in the evolution of livini:' mattci-. 



