THE CONTINUITY OF THE GERM-PLASM 5 



two germ-cells, one from each parent, and these again were each 

 derived by single lines of descent (i.e. lines in which no con- 

 jugation occurred) from the fertilized ovum whence each parent 

 sprang. Never in all the generations between fertilized ovum 

 and fertilized ovum does conjugation take place. The somatic 

 cells of the parent, therefore, as far as we know, contribute no living 

 elements to the child ; they merely provide temporary shelter and 

 nutriment. The child, therefore, does not, as is popularly supposed, 

 resemble his parent because his several parts are derived from 

 similar parts of the parent his head from his parent's head, his 

 hands from his parent's hands, and so forth ; he resembles him only 

 because the germ-plasm which directed his development was a 

 split-off portion of the germ-plasm which directed the develop- 

 ment of the parent. The egg produces the fowl, but the fowl 

 as a whole does not produce the egg only one cell from the fowl, 

 the fertilized ovum, produces it. 



9. The germ-cells are, in a real sense, immortal. Saving acci- 

 dents, they divide perpetually, and at intervals conjugate, and there 

 is no dead body. In like manner the germ-plasm is potentially 

 immortal. It grows and divides into separate portions, but does 

 not die unless killed or starved. Each fertilized ovum builds, 

 with mortal cell-descendants, a temporary dwelling, the body, 

 around its potentially immortal descendants, the germs, which 

 hand on to succeeding generations their all-important trust, the 

 germ-plasm. Thus there is ' continuity of the germ-plasm! This 

 conception of continuity is one of the main pillars of the modern 

 science of heredity. It is of very recent origin. Darwin, for 

 example, believed that the somatic cells emitted minute living 

 representatives, * gemmules,' as he termed them, one of which from 

 each cell found its way to each germ and re-constituted the germ- 

 plasm. The germ-plasm, therefore, was supposed to be formed 

 afresh in each germ, when, of course, there could be no continuity ; 

 and the various parts of the child would be derived from corre- 

 sponding parts of the parent. It is now known, however, that the 

 information on which Darwin relied was founded on a mistaken 

 interpretation of the facts. Contrary to what he supposed, the 

 evidence is massive that parental ' acquirements ' are never ' trans- 

 mitted ' to offspring. 



10. Under the constant direction of its hereditary tendencies 

 the fertilized ovum proliferates, and the cell-community thus 

 originated grows (develops) through the continued but regulated 

 multiplication of cells, and so takes shape as an 'individual,' 



