Evidence from Protozoans ,'397 



Concliulinc/ Rcmdrk on Ei^Ulcncc Presented 



Our objective study of tlic production of licrcdit ;ir\ 

 structures and activities in the proto/oa niav u<II <iid with 

 a comment on a parafrraj)li occnrriiin in one of ("alkiiis' aUh- 

 and useful ])a])ers. In the general conchisions of this |>a|Mr 

 we read: "The chromatin, in addition to h( irii^^ the recog- 

 nized agent in lieredity, is also o(.nerallv rec-o^nizi-d a> thr 

 center of formative clian^es in the ordinary vcTrctative ac- 

 tivities of cell life. Recent observations have })een inter- 

 preted to show that it is the seat of oxi(hitivc j)rocesses and 

 the direct agent in metabolism. These vai'ious ,Mi|)j)o.scd 

 functions of the chromatin are, in large part, infcreidial. 

 and there are no observations to show whether it alone is 

 the center of these various activities, or whetlier it phiVN 

 the part of middleman in the cell. I do not know wliethcr 

 it is possible to determine such a point." ^^ 



I ask the reader to note attentively this group of state- 

 ments. According to the opening words cliromatin is "the 

 recognized agent in heredity," while according to tlie last 

 sentence not only is such a role of the chromatin 'iargily 

 inferential" and there are "no observations to show" that 

 "it alone is the center" of such activity, but the author 

 frankly admits himself in doubt as to the possil)ihty of de- 

 termining such a point. 



What I chiefly wish to do in connection with this is to 

 insist that such facts as we have just been examining, some 

 of which were discovered by Calkins luinself, relati\(> to t h« 

 participation of non-cliromatic parts of the cell in th« 

 ontogeny of many protozoans, are, according to my int( r- 

 pretation, conclusive evidence that chromatin is nat nlom 

 the "center" of activity of hereditary divelopment. I'or 

 the rest I do no more in this chapter tlian call attention 

 to the fact that further discussion of tin- mattir at issue is 

 not biological in a strict sense, but is i)art of the problem 



