REVIEWS 165 



carefully selected, and seem to be admirably adapted to the needs of the more 



advanced student : through the memoirs mentioned the rest ot the literature can 



generally be found pretty easily. We note with pleasure that at last due credit is 



given to English-speaking workers. The illustrations originally prepared were 



destroyed by fire just as the book was finished — a catastrophe which would have 



broken most people's hearts. We feel sure, despite the author's suggestion to the 



contrary, that they were better than their substitutes. From the practical point of 



view the book is too heavy (it weighs more than seven pounds) and too expensive. 



The discredit of the weight belongs to the publishers : it seems a pity that the high 



reputation of the Oxford University Press in these matters should be endangered 



by their taking American printing under their wing. The price might have been 



reduced by the omission of many of the unnecessary coloured plates : the student 



who does not know from practical experience what haemin crystals look like is 



hardly fit to read the book at all. 



A. E. Boycott. 



The Causation of Sex. By E. Rumley Dawson, L.R.C.P., M.R.C.S. [Pp. 196.] 

 (H. K. Lewis. 6s. net.) 



We are told on the title-page and in the preface of this book that the hypothesis 

 advocated is a new theory of sex, based on clinical materials, as the result of 

 prolonged and careful study. But the comparative biologist will not be encouraged 

 by finding on the first page of the introduction that " the whole question of the 

 causation of sex in mankind had been hedged around, encumbered, and obscured 

 with observations ad nauseam on the eggs of the invertebrata ; on worms and 

 tadpoles ; on sponges and plants ; on bees and waterfleas ; and lastly on hens' 

 eggs, to which nothing more dissimilar could be found than the human egg or 

 ovum." The same kind of thing reappears elsewhere, e.g. p. 159. "In another 

 class of vertebrata — the reptilia — if we claim the causation of sex in woman is the 

 same as in snakes, we must, to be impartial, revise our ideas of respiration in 

 woman, owing to the undeveloped condition of one of the lungs seen in various 

 snakes." Such arguments do not inspire our confidence. 



But with the hypothesis itself we have no quarrel ; it can be tested only by 

 careful experiment, and if proved to be true will be a very important contribution 

 to the subject. Put shortly, it is, first, that the sex is already determined in the 

 unfertilised ovum, a statement with which we are in complete agreement, and 

 secondly that the right ovary in the human species and probably the mammalia 

 produces only male-bearing eggs, the left only female. This second part is 

 difficult to prove, for, as the author says, after ovariotomy a small portion of 

 ovarian tissue may remain, and may grow so as to produce functional ova. Almost 

 the only safe method of testing it is to find whether a corpus luteum in the right 

 ovary is always associated with a male foetus, and he produces a large number of 

 cases in support of his contention. 



But the author is mistaken when he supposes that his theory is quite new : we 

 understand that in parts of Ireland the same belief has long been held, with the 

 addition that if the woman lies on the right side at the time of conception a male 

 will be born, if on the left a female. Mr. Dawson makes a similar suggestion, 

 that the preponderance of male births is partly due to the habit of lying on the 

 right side, so making the fertilisation of an ovum from the right ovary more 

 certain than from the left. 



A further important point is that ovulation takes place alternately from right 

 and left ovaries, so that after a child has been born, if the number of menstruations 



