ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 535 



is associated with the partial or complete suppression of one form of 

 gamete, the male eg.;. Parthenogenesis, on the other hand, entails the 

 occasional, or the cyclical, arrestment of one or other of the two gametes 

 of the female. If it hecome acyclical (Weismann) with the consequent 

 disappearance of the males, with these there vanish the male-eggs which 

 produce them, and the spermatozoa. In such instances the only form of 

 gamete left is the female-egg, which, as is well known, undergoes an 

 isogamous union with a rudimentary sister, the polar body. 



The problems of the origin, the determination, and the regulation 

 of sex should be more carefully distinguished. " Of its origin no abso- 

 lutely certain knowledge is possible." " The actual determination is 

 initiated at the division of the primary germ-cells into secondary ones ; 

 it is completed at the formation of the oocytes and spermatocytes, and 

 its manifestation is accomplished by the numerical reduction of the 

 chromosomes in these." 



The experiments of Yung, Born, &c. were really experiments in the 

 regulation of sex, and only prove what percentage of either sex will 

 survive under given, usually utterly abnormal, conditions. The so-called 

 self-regulation of the proportions of the sexes is mainly due to the pre- 

 ponderance of the males in the earlier, and of the females in the later 

 offspring. An incremert in the race is effected by increasing the number 

 of offspring, and with these the number of females. The adjustment 

 begins to manifest itself in the third generation. 



Determination of Sex.* — A. Van Lint expounds a new theory of 

 the determination of sax, whicli seems to be in part a rejuvenescence of 

 Starkweather's. The theory is that the offspring has the sex of the 

 weaker parent, but the weaker parent comes to mean the parent whose 

 sex-cells were relatively less vigorous at the time, and this, unfortunately, 

 cannot be readily tested. 



In the first part of the little book, Van Lint frankly and lucidly ex- 

 pounds the five hypotheses involved in his theory : — (1) The ovum and 

 spermatozoon are antithetic, they express opposite extremes of cellular 

 ditferentiation, or it may be that they differ like right-handed and left- 

 handed crystals. (2) There is also a somatic antithesis between the 

 ma«culine body and the feminine body, often conspicuous in secondary 

 sexual characters, often inconspicuously expressed in minute contrasts 

 throughout the soma. (3) There is also a contrast between the germ- 

 cells produced by an individual organism and the soma of that organism; 

 they are complementary expressions of an original hermaphroditic 

 unity ; the characters of the sex suppressed in the development of the 

 gonads are reflected, as it were, in saturating influence on the soma. 

 (4) So strong is this contrast that the male's somatic cells — which the 

 author calls parova — may be regarded as sexually equivalent to ova, 

 while the female's somatic cells — which the author calls paraspermato- 

 zoids — may be regarded as sexually equivalent to spertmtoz ia. (5) The 

 properties of the somatic cells may modify the properties of the sex- 

 cells in embryonic as well as in adult life, and this in such a precise 

 way that they determine the sex of fie offspring into which the germ- 

 cells will develop. 



* QuVst-C2 qui determine le soxe? Paris, 1902, 77 pp. 



