THE ULTIMATE SEX-ELEMENTS. 93 



organs are later in making their appearance, or at least they are 

 only detected at a later stage ; and it must also be pointed out 

 that, in cases of alternation of generations, an entire asexual 

 generation, or more than one, may intervene between one ovum 

 and another. 



§ 8. Body Cells and Reproductive Cells. — Various naturalists 

 have insisted on the contrast hinted at above, between the cells 

 of the embryo which go to form the body, and those which are 

 set apart as reproductive organs. 



(<?) As early as 1849, Owen noted that, in the developing 

 germ, it was possible to distinguish between cells which became 

 much changed to form the body, and cells which remained 

 little changed and formed the reproductive organs. This view, 

 as Brooks points out, he unfortunately afterwards departed from 

 in his Anatomy of the Vertebrates. 



{b) In 1866, Hoeckel connected reproduction with discon- 

 tinuous growth, and insisted upon the material continuity 

 between parent and offspring. Somewhat later, both he and 

 Rauber drew a clear contrast between the somatic and repro- 

 ductive elements, between the " personal " and " germinal " 

 portions of the embryo, or between the l)ody and the sex cells. 



{c) W. K. Brooks, in 1876 and 1877, again drew attention 

 to this significant contrast. 



{d) Yet more explicit, in 1877, was the ingenious Dr 

 Jager, now better known in a very different connection, and 

 a few of his sentences well deserve to be quoted. Referring 

 to a previous paper, he writes as follows : — " Through a 

 great series of generations, the germinal protoplasm retains its 

 specific properties, dividing in every reproduction into an 

 ontogenetic portion, out of which the individual is built up, 

 and a phylogenetic portion, which is reserved to form the re- 

 productive material of the mature offspring. This reservation 

 of the phylogenetic material I described as t/ie continuity of the 

 gcrni-p7'otoplasni. Encapsuled in the ontogenetic material, the 

 phylogenetic protoplasm is sheltered from external influences, 

 and retains its specific and embryonic characters." 



ie) In an exceedingly clear manner, to which sufficient 

 attention seems hardly to have been accorded, Galton, in 

 1876 and at other dates, as again more indirectly in his recent 

 A^atural Inheritance., drew attention to the contrast between the 

 gemmules of the ovum (stirp) which go to form the body, and 

 those which, remaining undeveloped, form the sex-cells. " The 



