33C Report S.A.A. Advancement of Science. 



4. THE GERM-CELLS VIEWED AS STORE-HOUSES OF 

 STIMULI, AND THE PRINCIPLE OF EQUILIBRATION 

 BETWEEN THE SOMA AND THE GERM-CELLS. 



The higher animals and plants differ from such lowly organised 

 forms as Afuaba and Heteromita in that the body is composed of a 

 number of cells instead of a single one. and this number is usually 

 very large. The majority of these cells become specialised in various 

 directions to form the various tissues of which the body is com- 

 posed, and may. therefore, be distinguished as somatic or body forming^ 

 cells. A certain number, however, remain unspecialised. and form 

 the germ-cells. These retain to a large extent the characters of 

 primitive unicellular organisms {Protozoa), and are alone capable 

 (in most cases) of separating themselves from the organism, and 

 giving rise by a process of cell-division and progressive differentia- 

 tion to a new individual of the same kind as the parent. 



Admitting, with Weismann and others, that the nucleus of the 

 germ-cell is the seat of the hereditary tendencies which mould the 

 new organism into the form of the parent, the question arises : " How 

 do these hereditar}' tendencies, or latent stimuli, come to be stored up' 

 in the nucleus of the germ-cell ? "" 



Darwin, we know, imagined the existence of minute " gem- 

 mules '" which were supposed to migrate from all parts of the body 

 to the germ-cells, . there to be stored up until required later on to> 

 control the development of the new organism. Weismann, on the- 

 other hand, supposed that the hereditary tendencies were located in 

 certain minute bodies which he called determinants, and that these 

 determinants were present in the germ-cells so to speak ab initio, 

 being handed on from generation to generation by the continuity 

 of the germ-plasm. He further maintained that the germ-cells are 

 separated from the somatic cells at an extremely early date, and 

 that they cannot be influenced by the surrounding bodv or soma, 

 with the necessary corollary that .somatogenic characters, acquired 

 in the lifetime of the individual, cannot be transmitted to the next 

 generation. This point we have already had occasion to discuss, 

 and we need only point out here that Weismann's theory in this 

 respect is directly opposed to that of Herbert Spencer, as expressed 

 in the following paragraph : — 



" It is an unquestionable deduction from the persistence of 

 force that in every individual organism each new incident force must 

 work its equivalent of change; and that where it is a constant or 

 recurrent force the limit of the change it \\ orks must be an adaptation 

 of structure such as opposes to the new outer force an equal inner 

 force. The only thing open to question is, whether such readjust- 

 ment is inheritable; and further consideration will, I think, show 

 thatto say it is not inheritable is indirectly to say that force does not 

 persist. If all parts of an organism have their functions co-ordinated 

 into a moving equilibrium, such that ever}- part perpetually influences 



