252 SUMMARY OF CURRENT RESEARCHES RELATING TO 



but do we know that the growth of antlers can affect the gonads in a 

 specific and representative way, which is what requires to be proved if 

 " modifications " are transmissible ? The gonads affect the nasal organ 

 in man in many ways, but is it really " obvious " that the nose affects 

 the properties of the gonads ?] 



(7) " If, as Weisinann supposed, the germ-cells were entirely un- 

 affected in their essential properties by the history and circumstances of 

 the body in which they were contained, it is impossible to conceive 

 how the removal of the generative organs could affect the development 

 of the tissues of that body." [We must protest again that the author is 

 too brief in his way of stating the views of others. Has not Weismann 

 most explicitly said that he does not hold that the germ-cells lead a 

 charmed life unaffected by somatic conditions? Is it not one of Weis- 

 mann's theories that germinal variations may be evoked as the result of 

 local fluctuations in nutrition?] 



(8) Why should secondary sex characters appear at sexual maturity, 

 and why should those of the male be restricted to the male offspring, 

 and thoso of the female to the female offspring? " The true explanation 

 an my opinion is, that heredity causes the development of acquired characters 

 for the most part only in that period of life and in that class of individuals 



in which they were originally acquired." [The underlined words of this 

 " explanation " seem to us to say that certain components in the inherit- 

 ance are not expressed unless the appropriate bodily conditions are 

 present, and that the time and conditions of their ontogenetic ex- 

 pression correspond to those of their phylogenetic origin. The first 

 clause is a truism; tho second, as the author clearly points out, is a 

 hypothesis.] 



(9) " I believe I may claim that my theory is, in its special details, 

 new and original. The theory of the inheritance of acquired characters 

 is, of course, old, and is regarded by many as extinct. But, so far as I 

 know, I have not been anticipated in my elaboration of this theory into 

 the form in which I present it, namely, that the direct effects of regularly 

 recurrent stimulations are sooner or later developed by heredity, but only i n 

 association with the physiological conditions under which they were originally 

 produced, and that this is the explanation of the limitation of particular 

 modifications, not merely to particular species or kinships, but to par- 

 ticular periods in the life of the individual, to a particular sex, and even 

 to a particular season of the year in that sex." 



Mr. Cunningham's work is always interesting and forcible, and, 

 apart altogether from his particular theory, the 250 pages devoted to the 

 discussion of particular cases form a useful- and welcome contribution to 

 the aetiology of sex. We have suggested some criticisms because the 

 author invited them, and not with any confidence that the problem of 

 t-exual dimorphism has been solved by any of the interpretations which 

 the author rejects. 



Sexual Season in Mammals.* — Walter Heape devotes the intro- 

 ductory part of his paper to a much-needed definition of terms : — repro- 

 ductive period, breeding season, sexual season (the particular time or 

 times of year during which the sexual organs exhibit special activity), 

 gestation period, nursing period, and so on. 



* Quart. Journ. Micr. Sci., xliv. (1900) pp. 1-70. 



