34 SUMMARY OF CURRENT RESEARCHES RELATING TO 



influence of mutual sterility. Gulick's segregation is again a mucli wider 

 conception, including many other separating factors ; nor does he restrict 

 its operation " within the limits of specific distinctions." 



In preliminary chapters, after historical matter and much-needed 

 definitions of terminology, Mr. Gulick endeavours to show that divergent 

 evolution is not explained by natural selection, nor by the " advantage 

 of divergence of characters," nor by natural selection plus great dif- 

 ference in external conditions, nor in fact by selection of any kind 

 whatever. 



The fundamental law to which he calls attention is expressed in the 

 following formula : — " Cumulative segregation produces accumulated 

 divergence ; and accumulated divergence produces permanent segrega- 

 tion ; and the segregate subdivision of those permanently segregated 

 produces the divisions and subdivisions of organic phyla." Segregation 

 may be produced by man [rationaf), or by nature outside of man 

 (responsive), and both these may be intensified by other principles of 

 independent transformation {intensional). Or again, he classifies segre- 

 gation as " environal" (relation to environment), "reflexive" (inter- 

 specific relations), and " intensive " (" enhanced by one or more forms of 

 intension "). 



The author seeks to show (1) that there is "in nature a law of 

 cumulative segregation," and granting this, (2) that " cumulative segre- 

 gation will produce accumulated divergence, without any selection in 

 the sense that natural selection is selection," in fact "that without 

 segregation no divergence of type will arise." (3) He proceeds to 

 analyse the conditions of cumulative segregation as A, Environal — 

 industrial, chronal, spatial, fertilizational, artificial (with subdivisions) ; 

 as B, Beflexive — conjunctional, impregnational, and institutional; and 

 as C, Intensive, with eight subdivisions. 



As an analysis of the conditions of association and isolation the 

 memoir possesses great interest, not a little spoilt by the elaborate and 

 ugly terminology. The author certainly cannot be charged with de- 

 preciating the complexity of the inquiry. The reader will naturally 

 seek for more information as to the existence of cumulative segregation 

 as " a law in nature," and for more evidence and explanation of the con- 

 tinued divergence of forms after they have been so separated or segre- 

 gated. Still the paper mainly professes to emphasize the importance of 

 inquiring into the conditions and effects of segregation, and in so doing 

 is valuable. 



Heredity.* — Prof. M. ISTussbaum sums up his views on the problems 

 of heredity. The homology of the germinal cells, their early differen- 

 tiation and relative isolation, the phenomena of regeneration, the trans- 

 mission of acquired characteristics, and the like, are discussed in a 

 manner with which the previous work of this author has made us 

 familiar. " The constancy of the species depends upon the uninterrupted 

 descent (Jaeger's continuity of the germinal plasma) ; the variability 

 depends upon the interaction of intrinsic and extrinsic forces. Selection 

 is a consequence of this interaction, since it always rests with the 

 numerical strength of the forces, whether the individuals and their 

 germinal material persist, change, or perish." 



* 'Ueber Vererbung,' 8vo, Bonn, 1888, 23 pp. 



