Referate. 159 



In Morgan's second paper he admits the simplicity of Castle's 

 suggestions, but says they are not adequate. His criticism is that without 

 the dual system it is difficult to represent heterozygous forms and practically 

 impossible to show gametic coupling. 



Emerson, in a very fair criticism of these three papers, shows that 

 the reforms suggested will not fit other Mendelian work. For example, he 

 says, "Who can point out the normal color of a bean?" Emerson believes, 

 with justice, that no simplified terminology should be adopted unless it will 

 express all of the current Mendelian formulae. Further, he thinks that 

 there is no great difficultly in understandig the present terminology or in 

 teaching it to students. He also emphasizes the fact that in cases where 

 "whites" exist with a number of different gametic formulae, as in the seeds 

 of maize, neither Morgan's nor Castle's scheme is simple or adequate. 



The trouble seems to be, as Emerson shows, that though both Morgan 

 and Castle seem to see the difficulty, they both attempt to force a letter 

 to represent a character, rather than a factor in a system of notation 

 that is concerned with other factors in the development of a character. 



E. M. East. 



Morgan, T. H. Heredity and sex. pp. 282, figs. 121, 1913. New York: 

 Columbia University Press. 



The Jesup lectures of the Columbia University, for 1912 13, give a 

 comprehensive view of the results of modern work on the inheritance of sex. 

 The eight lectures are published essentially as delivered, though only a few 

 of the splendid lantern-slides with which they were illustrated could be 

 included, and some of these have suffered considerably in the reproduction. 

 The lectures were addressed to a general biological audience and are in- 

 tended to give the general student of biology a fair notion of the work 

 which is being done in this special field, rather than to provide a hand- 

 book for the specialist. For simplicity and clarity of statement, the work 

 is a model. 



The treatment is almost wholly zoological and references to the sex- 

 problems in plants are made only when they have obvious bearing on those 

 of animals. The more or less incidental sex-relations among animals are 

 discussed at some length. The chief disadvantages of this strong zoological 

 orientation are seen in the implication that certain phenomena are funda- 

 mental which are, in fact, only incidental; thus in the second chapter, on 

 the mechanism of sex-determination, as in much of the modern zoological 

 literature, undue emphasis is laid upon the significance of the polar bodies. 

 Under ordinary circumstances, the peculiarities of the polar bodies have 

 nothing whatever to do with the mechanism of sex-determination. The naive 

 statement that "the egg deliberately, as it were, twice throws away its valu- 

 able heritage" places the emphasis on a wholly irrelevant fact. The reduction of 

 chromosomes, which is the one important feature in connection with the 

 formation of the polar bodies, takes place in the formation of the sperms, 

 where no chromosomes degenerate, quite as well as in the maturation of 

 eggs; and in the eggs of plants the cells which correspond to the polar 

 bodies of animals, apparently differ in no other way from the successful 

 egg-cells, except that they usually occupy a relatively more superficial position. 

 In plants also, they quickly degenerate and disappear, leaving to the single 

 remaining egg the capacity for further development and the production of 

 a new individual, but this process probably relates, in plants as in animals, 



