AND INHERITANCE IN PEDIASTRUM. 429 



for we have the visible organ or plastid of the cytoplasm to provide 

 for such transfer. The evidence as to the behavior of the plastids 

 in zygospore formation in Sp'irogyra indicates that the same is true 

 in sexual reproduction by cell fusion. In the case of the lobbed cell 

 form, however, every visible trace of the adult character as such 

 seems to be lacking in the germ cell, and it seems natural to postu- 

 late a gene or factor which without being the character itself may 

 as a granule or in some other form represent the adult form when it 

 his disappeared. As a matter of fact, however, we have no plastid 

 for form determination and to assume a granule like a plastid in the 

 chromosome which transmits the determiners of the adult cell form 

 meets with obvious difficulties in this case. The sudden appearance 

 of the lobed, spinous cell form in reproduction as I have described 

 it does not suggest the working out of influences emanating from ele- 

 ments in the chromosomal organization of the nucleus, but rather 

 the direct expression of the organization of the cell as a whole when 

 it begins to grow. This organization shows the most direct rela- 

 tions of adaptation to and interdependence with the pressures and 

 contacts established in such a group of cells and may well have been 

 achieved as a response to such environmental surroundings, but it is 

 quite independent of them and comes to full expression, as noted, in 

 cells which are for accidental reasons quite free from the other 

 members of the colony. It seems to me to be most obviously the 

 expression of the anomogenous organization of the protoplasmic 

 mass involving localized growing points on its surface, specific polar 

 differentiations, etc. This general organization of the cell may well 

 be transmitted indirectly through cell division involving as such 

 transmission would only a sort of regeneration by each daughter 

 cell of the general symmetry relations between the parts of the 

 mother cell. 



We do not need, then, as it seems to me, to imagine any spatially 

 differentiated organization of a special germ plasm to account for 

 the inheritance of cell form in Pediastrum. It would be possible, 

 but probably premature, to attempt to express in diagrammatic form 

 for Pediastrum the organization of the cell as a whole which is im- 

 plied in its behavior in forming the colonies. Much further cyto- 

 logical work such as has been done by Smith on nuclear and cell di- 



