ANIMAL PRODUCTION. 173 



the course of development are " secondary teleones." The manner in which they 

 are thought to function in heredity is explained in detail. 



Studies in the experimental analysis of sex, G. Smith {Quart. Jour. Micros. 

 ,s('/. [London], n. sen, 5-i {1910), No. 216, pp. 577-60.',, pi. i).— This is a paper 

 on sex heterozygotism, in which the author reports his observations on several 

 species of invertebrates and discusses the different theories of Mendeliau in- 

 lieritance of sex. 



An examination of several thousand specimens of a species of spider crab when 

 liarasitized by a cirripedian showed that the infected male assumed female 

 c-haracteristics in varying degrees of perfection, even to the development of 

 ova in the testis. The female, however, never took on such secondary male 

 characters. Other facts are cited which support the theory that in many 

 species of animals one sex, either male or female, is always a sex hybrid, 

 while the other is pure. According to the author the sex hybrid may appear as a 

 male, a hermaphrodite, or a female according to some unknown physiological 

 condition, and that external influences may give a bias to a heterozygous embryo 

 to appear as either male or female. It is pointed out that sex may not neces- 

 sarily be a simple unit character but, on the contrary, that the sex character- 

 istics fall into 2 divisions, primary and secondary. 



Reasons are given for assuming that there is an internal secretion which is 

 continually changing in development, and acts and is acted upon by the various 

 organs of the body. It is also assumed that this sexual formative substance 

 or generative ferment (Heape) has male and female modifications which are 

 allelomori)hs, giving rise to the half hybrid nature of sex, but only future in- 

 vestigations can show under what physiological conditions one sex may gain 

 the upper hand. The author's theory of the correlation between primary ana 

 secondary sexual characteristics differs from Cunningham (E. S. R., 21, p. 

 170) in assuming that there is some common factor back of both primary and 

 secondary characteristics. 



Sex and sexual characters, J. T. Cunningham {ScL Prog. Twentieth Cent., 

 Jt {]'.)10), Ao. 15, pp. Ji57-.'f73). — The view is expressed that Doncaster, in sup- 

 porting the Mendelian view that sex is the property of gametes (E. S. R., 22, 

 p. 273), has failed to account for the artificial development of secondary sexual 

 organs by means of chemical stimulation which has been obtained by Shat- 

 tock and Seligmann with poultrj', Nussbaum with frogs, and Starling and 

 Claypon with rabbits. Several cases are used to illustrate wherein the author's 

 view differs from Doncaster's. " If we make the weak ovum correspond with 

 the male-bearing ovum, the selective union is betvA'een gametes of the same sex, 

 not of opposite sexes — the weak ovum unites with a strong sperm and the lat- 

 ter is dominant. Thus, the sex is not determined by the ova alone or by the 

 sperms alone, but by whichever is stronger, that is, the more vigorous are domi- 

 nant." The distinction between adaptive and nonadaptive characters is thought 

 to be the same as that between continuous and discontinuous variation. 



The heredity of sex, F. Keeble {Nature [London], 82 {1910), No. 210.',, pp. 

 Ji87, J,SH). — Instead of assuming that the phenomena of sex are due to a single 

 pair of alleloniorphic characters, the author proposes a hypothesis of 2 inde- 

 pendent pairs of characters, namely, " maleness (M), with ifs allelomorph, 

 al)S(>iice of maleness (m), which constitute one pair, and femaleness (F), with 

 its allelomorph (f), which constitute the other pair. On this hypothesis, since 

 Mm, Ff are independent of one another, representatives of both pairs of char- 

 acters occur in every gamete. 



"All gametes are therefore of one or other of the following sex constitutions, 

 MF, Mf, mF, mf. Hence all zygotes produced by the pairing of such gametes 

 are of one or other of the following nine gametic constitutions: 1 MMFF, 



