GENERAL ARGUMENT FOR 203 



In many simple animals, such as sponges and hydroids, the 

 germ-cells simply make their appearance at certain times of year 

 among the commonplace somatic cells. In many plants the 

 distinction between body and germ-cells can hardly be drawn 

 until the period of reproduction sets in. Thus Spencer refused 

 to accept the contrast between body-cells and germ-cells as 

 expressing a fact, and referred to the numerous cases in which 

 small pieces of a plant or a polyp may grow into entire organisms. 



To this objection Weismann answers, — (1) that the distinction 

 between somatic cells and germ-cells has been gradually em- 

 phasised in the course of evolution, and that in the simpler 

 multicellular organisms it is still incipient ; (2) that it is quite 

 conceivable that, even in some complex organisms, the body-cells, 

 though differentiated, may retain some residual unused germ- 

 plasm ; and (3) that there may be a quite definite and distinct 

 germ-plasm, though there is no demonstrably distinct lineage 

 of germ-cells. 



Again, however, we must remember that the blood, or lymph, 

 or other body-fluids form a common medium for all the parts 

 of the animal, gonads included ; the results of changes in nutrition 

 may saturate throughout the body and affect the germ-cells inter 

 alia. The nervous system makes the whole organism one in a 

 very real sense ; in plants there are often intercellular bridges 

 of protoplasm binding cell to cell, and this is true in not a 

 few cases among animals. Moreover, there are subtle, dimly 

 understood correlations between the reproductive organs and 

 the rest of the system. If changes in the reproductive organs 

 can effect changes in remote parts, such as the larynx and the 

 mammary glands, why may not there be reciprocal influences ? 

 In short, the organism is a unity, and to divide it up, in any hard- 

 and-fast way, into soma and germ-cells may land us in the same 

 fallacy as parcelling the mind into separate faculties. 



It must be admitted, therefore, that it is quite erroneous to 

 think of the germ-cells as if they led a charmed life, uninfluenced 



