via OBITUARY NOTICES OF MEMBERS DECEASED. 



explain the origin of death as an adaptation due to selection was 

 probably a mistaken one. 



As to the location of the germ-plasm in the sex cells Weismann 

 maintained that it was to be found in the chromatic substance of 

 the nucleus. He held that the chromosomes ("idants") were 

 composed of smaller units, the chromomeres ("ids"), and that the 

 latter were composed of " determinants " or inheritance units, while 

 the most elementary units of life he called "biophores." Both 

 chromosomes and chromomeres are visible structures of the cell. 

 Determinants and biophores are ultra-microscopic in size but re- 

 cent work on heredity and development has shown that there is 

 good evidence of the existence of such units. All recent work in 

 genetics is based upon the hypothesis that there are units or factors 

 or determiners in germ cells which condition the development of 

 adult characters, and though there may be minor differences be- 

 tween these determiners of modern genetics and the determinants 

 of Weismann no one can fail to note the genetic connection and the 

 family resemblance between the two. 



His prediction on purely a priori grounds that one of the 

 maturation divisions in the formation of the egg and sperm should 

 be a " reduction division" whereby the chromosomes of the sex 

 cells should be reduced to half the number present in the somatic 

 cells, whereas all other cell divisions should be " equation divisions " 

 in which the chromosomes should divide equally, was almost as 

 brilliant an example of scientific prophecy as was the prediction of 

 the existence of the planet Neptune. 



Similarly Weismann's assumption that the determinants are ar- 

 ranged in a linear series in the chromosomes finds strong support in 

 the newest and most striking discoveries in this field, in which 

 Morgan is able to locate at different points along the length of a 

 chromosome the determiners of many developed characters. 



Finally there is at present universal agreement to the declara- 

 tion of Weismann that no purely epigenetic theory of heredity 

 is possible, though for many years even this was hotly contested. 

 When one recalls the storm of opposition which was called forth 

 by his book on " The Germ-Plasm " the present acceptance, at least 



