CYTOPLASM AND ACTIVATION OF THE GENE 265 



with the elaboration of manifold substances, having to do 

 obviously with the growth and probably also with the chemo- 

 differentiation of the cytoplasm. A direct demonstration of 

 the relations is available only in the experiments of Haemmerling 

 (page 192), which show that the intact nucleus controls the 

 production of formative substances, showing a gradient away 

 from the nucleus. But we do not know how and where they or 

 their precursors are elaborated under the control of the nucleus. 

 Thus we must be content to know that certain decisive cyto- 

 plasmic activities and differentiations are controlled by the 

 nucleus, i.e., by the genes, without being able yet to follow 

 chemically the details of these interrelations. (A theory to 

 account for the facts of development in rather the opposite way 

 from the one usually assumed by geneticists has been published 

 recently by Just, 1936). 



It may be added that Koltzoff (1935) thinks that some sub- 

 stances that are difficult to synthesize are actually identical 

 with genes, w r hich produce their like by assimilation and give 

 off the surplus into the cytoplasm. Davenport (1935) thinks 

 that the genes lie near the surface of the nucleus. They attract 

 cytoplasmic molecules with the opposite charge. The residual 

 charge suffices to attract another molecule to the second, resulting 

 in making the two cytoplasmic molecules independent of the gene- 

 molecule, which starts the same process over again. It must be 

 honestly said that thus far this problem has not found any 

 factual or theoretical solution. 



2. THE ACTIVATION OF THE GENES 



The second question concerns the activation of the genes. 

 If genes control definite cytoplasmic processes occurring at 

 definite times in development, e.g., the production and flow of 

 the organizer substance in amphibian development, they are 

 supposed to be activated at the proper moment to set in motion 

 the cytoplasmic process. We have already reported the many 

 facts that demonstrate the time of onset of genie action in 

 different cases, ranging from the very end of differentiation 

 down to the behavior of the first segmentation spindle. In 

 order to form a general idea of these processes of activation, we 

 may describe them as follows. Whether the genes are catalyzers 

 or not, the decisive immediate product of their action must be 



