216 SUMMARY OF CURRENT RESEARCHES RELATING TO 



produced ; while when the motlier is weakly or less adapted for 

 procreation the result is a girl. lu the former case the mother's 

 influence is predominant, in the latter she is more indifferent than the 

 male ; or, in other ^vords (and, indeed, in the terms of a very widely 

 distributed belief) the peculiarities of tlio mother pass as a rule to 

 the son, and those of the father to the daughter. The predominant 

 importance of the mother is to be expluined by the facts that un- 

 fertilized eggs may become developed into viable organisms (parthe- 

 nogenesis of insects), that ovarian dermoid cysts are due to a real though 

 an incomplete development of the ovum, and that the spermatozoon 

 lives for a shorter period than an ovum. The reviewer suggests that 

 the cause of a larger number of males being produced after a war is 

 not, as the author thinks, due to the increased social advantages 

 dependent on less rivalry and to an increased activity, but to the 

 enfeeblement of the males and to the quiet life led by females during 

 the period of war. Polygamous marriages, one result of which is 

 tbat females do not have children more than once in two or three 

 years, have for another a great preponderance of male births, and so 

 prove the influence of the mother on the birth of sons ; prosj)erou8 

 years are also favourable for the production of males. The hypothesis 

 of Kicharz is supported by the facts that from unfertilized eggs 

 among insects only males arise [but this, which is true of Apis, is not 

 true of Ajnis, where we have thelytoky in the latter as well marked 

 as arrenotoky in the former case ; and obviously parthenogenetic 

 crustaceans, as well as insects, ought to be taken into consideration] ; 

 among hybrids — when the ovum is under its normal physiological con- 

 ditions, but the semen under more or less abnormal — males are most 

 common, and more resemble the mother. The experiment of Fiquet, 

 a farmer in Texas, who was able to determine the sex of the progeny 

 by different modes of feeding the mother, is referred to. On the other 

 hand, madness seems most often to pass from father to son, and from 

 mother to daughter ; the proportion being 53*3 to 46 • 6 per cent. 



New Law of Variation.* — W. K. Brooks quotes and approves 

 Dr. Diising's papers on the laws which regulate sex, and his state- 

 ment that a favourable environment causes an increase in the number 

 of births of female childi-en, while an unfavourable environment 

 causes an increase in the number of male births. 



Mr. Brooks believes that this is only part of a still wider gene- 

 ralization, and quotes facts to show that the male cell causes variation, 

 while the ovum transmits the hereditary characteristics of the species. 

 The union of two sexual elements has been evolved for the purpose 

 of securing variability, and the male element has gradually acquired, 

 by division of labour, the peculiar function of exciting variability to 

 meet changes in the condition of life. So long as the conditions of 

 life remain favourable there is no need for variation, but whenever 

 any unfavourable change takes place variation becomes necessary to 

 restore the harmony between the organism and its environment. If 

 this view be true, we have in Diising's results an exemplification of 



♦ Johns-Hopkins Univ. Circulars, iv. (1884) pp. H-IS. 



