265 



ing up of the bodily framework in which the germ-cells find 

 lodgement. 



Further, the somatic-cells, aggregated as they are into groups 

 constituting the various tissues and organs of the body, become 

 subject to the action of the environment, through and by which 

 they can be modified in various ways during the life-time of the 

 individual. Modifications resulting from such causes are the 

 acquired, or somatogenic characters of Weismann, and according 

 to his view, they can in no case influence the germ-cells and 

 appear in the products of these as congenital or blastogenic 

 characters. The germ-cells on the other hand difier toto ccelo 

 from the somatic, inasmuch as they are the receptacles of the 

 imperishable germ-plasm, and have no connection with the 

 somatic-cells save that the former are sheltered and nourished 

 by the latter. This germ-plasm took its origin in primeval uni- 

 cellular organisms, and has been handed down from these through 

 remote ages through them and through all the generations of 

 multicellular organisms which, in the course of evolution, suc- 

 ceeded the unicellular; or putting these abstract propositions 

 more concretely, suppose a new individual to be formed by the 

 union of the germ-plasm of two parent organisms, a portion only 

 of this admixture is used up in the formation of the said indi- 

 vidual, a certain residual fraction remains stored up in its repro- 

 ductive cells to be, in its turn, handed over to a member of the 

 next generation. This successive transference from generation 

 to generation represents that continuity of germ-plasm which is 

 the central feature of Weismann's theory. Again, we must 

 assume that these successive fragments, which are passed on 

 from individual to individual, grow and multiply at the expense 

 of the somatic cells of each individual in which they find lodge- 

 ment. Whilst thus however growing and multiplying the germ- 

 plasm itself faithfully preserves the chemical and molecular 

 qualities of that primeval fragment which the first sexual parents 

 passed on to their first ofispring. To make these statements still 

 clearer let me borrow from Sir William Turner the following 

 graphic mode of expressing the above facts.* 



A B C D. 



a ab abc ahcd. 



Let the capital letters, A B C D, express a series of successive 

 generations. Suppose A to be the starting point and to represent 

 the somatic or personal structure of an individual, then a may 

 stand for the reproductive cells, or germ-plasm, which the off- 

 spring of A, viz., B, is produced. 



* The idea would have been better conveyed if the small letters had been 

 included withm the capitals. 



