No. 533] NUCLEUS AND CYTOPLASM IN HEREDITY 



mechanism and inciting agent, the character of the re- 

 sponse depending both upon the constitution of the cyto- 

 plasm and the material (enzymes? nutritive substances?) 

 emanating from the nucleus. ' ' 



If we consider that the supplying of the proper amounts 

 and kinds of ferments is one of the important functions 

 of the chromosomes, then we may suppose that in bi- 

 parental inheritance each set of chromosomes is opera- 

 ting, probably catalytically, on a series of fundamental 

 cell constituents that are largely common to both lines of 

 ancestry: and that slight constitutional or configura- 

 tional differences in corresponding enzymes bring about 

 individual differences such as we recognize in the adult. 

 We have already seen that different ferments within cer- 

 tain limits may act on the same substance and yield dif- 

 ferent results; consequently, in the intrusion into the 

 egg of slightly altered enzymes in the chromosomes of 

 the male, we should expect corresponding structural 

 modifications to result. 



It is not the intention to imply, however, that all char- 

 acter changes must be chromosomal in origin. Any influ- 

 ence which could effect constitutional or configurational 

 changes in other essential constituents of the germ-cell 

 would doubtless produce corresponding alterations in 

 the adnlt. It is probable that not only changes of nuclear 

 origin are reflected on to the cytoplasm, but that, con 

 versely, cytoplasmic alterations may affect the nuclear 

 constituents, for we have already seen how even the sub- 

 stratum may modify the enzyme factors in entire organ- 

 isms such as molds and yeasts. Furthermore, there is 

 no reason apparent why if the differences, no matter how 

 produced, are modifications in the fundamental consti- 

 tution or stereometry of the material affected, they should 

 not persist permanently in the new germ-cells. 



It would seem, in fact, that in the permanent effects of 

 such reciprocal influences as here depicted for nucleus 

 and cytoplasm, we might be able to account in large 

 measure for the accumulations which have step by step 

 been grafted on to the primitive protoplasm in its epi- 



