1899] A COMPLEMENTARY MALE 15 



found a careful student in Mr. A. Gruvel {Arch. Biol. xvi. 1899, pp. 

 27-47, 1 pi.). In Hoek's Challenger Report there is some account of 

 the complementary male of Sc. regiuni, which is said to have two ganglia, 

 a functionless stomach, and cement glands, but not much else. In the 

 species studied by Gruvel the male is also very simple. It has two 

 ganglia and an eye, but no digestive canal nor specialised vascular and 

 respiratory apparatus. It is little more than an independent testicle 

 endowed with a minimum of individuality. 



Mr. Gruvel finds it difficult to admit that similar eggs fertilised by 

 spermatozoa of the same origin produce larvae destined to give rise, 

 some to hermaphrodites and others to these pigmy males. And so he 

 has thought out a theory which may render the affair less mysterious, 

 though we are not at all confident that it does. Cirripeds are usually 

 protandrous, i.e. the spermatozoa ripen before the ova. The sperms are 

 shed first, and accumulate in the interpallial space. By and by the ova 

 pass into the ovigerous sac, and are there fertilised ; as they develop, 

 the gaps in the sac are closed, and the whole is detached from the 

 genital atrium to be fixed to the ovigerous frenum. Thereafter there 

 emerge belated ova which have a poor chance of being fertilised by the 

 spermatozoa of the hermaphrodite. And Gruvel's theory is that these 

 are fertilised by the spermatozoa of the complementary male, which are 

 usually longer of developing than those of its bearer, and that from 

 these ova thus fertilised complementary males are produced. 



Is Fertility Inherited ? 



In the sixth of his valuable memoirs entitled " Mathematical Contribu- 

 tions to the Theory of Evolution," Prof. Karl Pearson, with the assist- 

 ance of Miss Alice Lee and Mr. Leslie Bramley-Moore, brings forward 

 evidence to show that fertility is inherited in man, and fecundity in the 

 horse, " and therefore probably that both these characters are inherited 

 in all types of life " — in all likelihood according to the Galtonian rule. 

 We have only seen the abstract in the Proceedings of the Poyal Society 

 (lxiv. 1899, pp. 163-167), but that is enough to show the interest and 

 importance of this inquiry, especially in connection with " reproductive 

 or genetic selection " — a term (which seems to us unfortunate) used to 

 describe " the selection of predominant types owing to the different 

 grades of reproductivity being inherited, and without the influence of a 

 differential death-rate." 



Mr. Pearson points out that the problem of whether fertility is or 

 is not inherited is one of very far-reaching consequences. " The 

 inheritance of fertility and the correlation of fertility with other 

 characters are principles momentous in their results for our concep- 

 tions of evolution ; they mark a continual tendency in a race to 



