190 WARFARE IN THE HUMAN BODY 



a catalytic or determining nature. And if this is correct 

 it follows, from all we know of iron-using bacteria to the 

 latest hypo- or hyperthyroidal patient, that these sub- 

 stances, however simple or complex, can be added or taken 

 away, and that in the food, or in successive metabolic 

 states resulting from its use, new catalysts may be formed, 

 combined or changed, as they can be by environmental 

 stimuli such as light. When saying so much it should be 

 added that I am aware of the work done, which, in certain 

 cases, shows, or seems to show, that there is an early 

 isolation of a germ-cell, ex hypothesi, containing the unim- 

 pressionable "germ-plasm." Yet whatever may be found 

 with regard to the embryo of a shark, or any of the cases 

 held to prove such early specialization, the facts are 

 insufficient on which to found a general law. They afford 

 no explanation of budding or repair, or the cases in which 

 " germ-cells " are wandering amoeboid bodies, and even 

 blood-cells, or of the so-called germinal epithelium itself. 

 To speak, as is often done, of specificity of detail as being 

 determined wholly by chromosomatic facts, without re- 

 solving the magic of " specificity" into definite " tools," is 

 surely idle. It is concealed vitalism. Nor do we really 

 learn much when we are told that in certain cases germ- 

 cells do not arise from ccelomic epithelium, but that they 

 migrate from special germ-areas into the gonad, since there 

 are so many different ways in which such specialization 

 begins. 



To show that the natural tendency of the physiologist is 

 to accept such a view as transmission Starling may be 

 quoted. His work on hormones, done in conjunction with 

 Bayliss, shows that he has a great appreciation of the power 

 of certain secretions to influence in the profoundest degree 

 digestive and metabolic processes. The possibility of 



