38 BIOLOGICAL SOCIETY OF WASHINGTON. 



upon the whole, arranged in a linear manner in the thin thread 

 like loops ; in fact the longitudinal splitting of these loops 

 appears to me to be almost a proof of the existence of such an 

 arrangement, for without this supposition the process would 

 cease to have any meaning" (pp. 359-360). 



His general view of the origin of variation is thus given by 

 him : "It is well known that this process [sexual or amphi- 

 gonic reproduction] consists in the coalescence of two distinct 

 germ-cells, or perhaps only of their nuclei. These germ-cells 

 contain the germ-substance, the germ-plasm, and this again, 

 owing to its specific molecular structure, is the bearer of the 

 hereditary tendencies of the organism from which the germ- 

 cell has been derived. Thus in amphigonic reproduction two 

 groups of hereditary tendencies are as it were combined. I 

 regard this combination as the cause of hereditary individual 

 characters, and I believe that the production of such characters 

 is the true significance of amphigonic reproduction. The 

 object of this process is to create those individual differences 

 which form the material out of which natural selection 

 produces new species " (p. 272). " I do not know what meaning 

 can be attributed to sexual reproduction other than the creation 

 of hereditary individual characters to form the material upon 

 which natural selection may work" (p. 281). "The most 

 important duty of sexual reproduction is to preserve and 

 continually call forth individual variability, the foundation 

 upon which the transformation of species is built" (p. 373). 

 " Sexual reproduction is to be explained as an arrangement 

 which ensures an ever-varying supply of individual differ 

 ences " (p. 384). 



Weismann's classification of cells into somatic and reproduc 

 tive is fundamental to his whole philosophy. On this point he 

 says : " The first multicellular organism was probably a clus- 



