HEREDITY AND ENVIRONMENT 185 



own subject, for the most part ignore all the related 

 sciences. With regard to pathology I have endeavoured 

 in some measure to make good this omission in the 

 remarks on Repair in Evolution, and although it is obvious 

 that the conclusions reached there are not likely to be 

 greeted with enthusiasm by those who hold the germ- 

 plasm theory, I shall not now lay any great stress upon 

 them. In this place it may be more pertinent to turn 

 to general histology, a subject which so far seems little 

 known to those engaged in biological study. For 

 nearly all work upon heredity appears to begin 

 with, and to be founded upon, a consideration of the 

 perfect gametes, and to proceed with elaborate accounts 

 of their reduction, maturation, and fusion in the zygote 

 without taking into full account the tissue history of the 

 organs in which they arise. In saying so much the in- 

 sistence on germinal epithelium is not overlooked, for 

 nowhere have I been able to discover why it is called 

 " germinal," except from the fact that in the higher 

 organisms the sperm and egg cells descend from epithe- 

 lium. Although in many of the lower kinds they 

 spring from blood cells, or other cells, this fact is inter- 

 preted by Weismannians as the pressing of germ cells 

 into general service, a view which is an outrage on logic. 

 It may be suggested that the tissue history of the 

 colony of epithelial cells in which they develop must 

 discover one very important fact, which is that they 

 have a special environment, and that when they are 

 " born," that is to say when they leave it for another, 

 the second or third place they occupy, though still an 

 environment, is less and less special as the growing cell 

 itself specializes. It seems to be forgotten that among 

 mammalians the offspring is at the least " born " three 



