Primary Actions 275 



secondary products are and what they do. Certainly Pontecorvo is 

 right, that the genetic methods for attacking these problems are 

 further advanced than the biochemical methods (a point which I 

 have made repeatedly in former works), but when the genetic analysis 

 is being transposed into biochemical terms, which we all enjoy doing 

 in a layman's way, or occasionally in a professional way, we may say 

 that we are swimming far out in the ocean with no land visible. I can 

 understand it when a biochemist, hearing about the present and 

 similar speculations of the geneticists, once said, "This is certainly not 

 biochemistry as we know it." 



B. THE INTRANUCLEAR SITE 



Whatever the origin of the primary genie products, and whether 

 or not they start reacting with their near neighbors at the very chro- 

 mosomal site, the primary or secondary products of genie action must 

 be found sooner or later within the nuclear sap, unless these products 

 stayed at the chromosomal site until a mitotic division allowed them 

 to be shed into the cytoplasm. 



This problem has been discussed many times (Stern, 1938; 

 Huskins and Steinitz, 1948; N. G. Anderson, 1953). It has many 

 aspects: the morphological one, which claims to show that formed 

 substances are visibly eliminated from the nucleus in interphase; the 

 genetical one, which tries to prove the point by showing that a genetic 

 action upon the gametes (or the gametophyte in plants) must have 

 taken place between two divisions (e.g., characters of starch in pollen 

 grains); and the biochemical approach, proving experimentally the 

 exchange of molecules through the nuclear membrane. 



In favor of extrusion of genie products at the time of mitosis is 

 an old observation of Conklin and Lillie that the determinative 

 processes in the mollusk egg are suddenly changed when the germinal 

 vesicle breaks down and its contents enter the cytoplasm. It is in 

 agreement with this observation that the oocyte nucleus contains all 

 kinds of structures in addition to the chromosomes (see, later, the 

 discussion of Brachet's work and of lampbrush chromosomes) and 

 that all these substances are poured into the cytoplasm when the 

 germinal vesicle disappears before the meiotic divisions. But it must 

 be kept in mind that the oocyte is a very special cell, in which not 

 only all the processes of genetically controlled predetermination take 

 place but also the accumulation of yolk, both of which are certainly 

 based upon nuclear processes, the latter function at least partially so, 

 since the cytoplasm also takes up DNA from outside sources. (See 



