517 
CHROMOSO.MES, HEREDITY AND SEX. 
stronger than those connecting chromosomes with Mendelian 
factors. 
In the third section the facts of sex-limited inheritance are 
discussed; these are regarded as strongly reinforcing the 
arguments of the two preceding sections. 
Lastly, certain difficulties are considered, and it is con- 
cluded that sex cannot be determined directly by the presence 
or absence of a factor Avhich merely determines whether an 
ovary or a testis shall develop, but that the determining factor 
causes a certain type of metabolism, which in turn leads to 
the production of one sex or the other. If such a metabolism 
is induced by other causes, an individual of one sex may 
probably arise from gametes which, in the absence of 
disturbing causes, would have given rise to the other sex. 
Eeferences. 
1. Agar, W. E . — “ The Spermatogenesis of L e p i d o s i r e n paradox a,’ 
‘ Quart. Journ. Micr, Sci.,’ 57, 1911, p. 1. 
2. Arinhruster, L. — “ Chromosonien verhiiltnisse hei der Spermato- 
genese solitarer Apiden,” ‘Arch, Zellforsch.,’ xi, 1913, p. 242. 
3. von Baehr, W. B. — “ Contributions a I’etude de la caryocinese, etc. 
(Aphis saliceti ”), ‘ La Cellule,’ xxvii, 1912, p. 385. 
4. Baltzer, F. — “ Die Chromosonien von Strongylocentrotus nnd 
Echinus,” ‘ Arch, f. Zellforsch,,’ ii, 1909, p. 549. 
5. “ Uber die Bezieliung zwischen dem Chromatin nnd der 
Entwicklung, etc.,” ibicl, v, 1910, p. 497. 
6. Bateson, W., and Pnnnett, R. C. — ‘ Reports to Evol. Committee of 
Roy. Soc.,’ iii, 1906, 9 ; iv, 1908, 10. 
7. “ On the Inter-Relations of Genetic Factors,” ‘ Proc. 
Roy. Soc.,’ B, Ixxxiv, 1911, p. 3. 
8. Berry, E. H. — “The Accessory Chromosome in Epeira,” ‘Biol. 
Bull.,’ xi, 1906. 
9. Blackman, W. M. — “The Spermatogenesis of Scolopendra.” 
‘ Bull. Mus. Comp. Zool. Harvard,’ xlviii, 1905, p. 1. 
10 . Bonnevie, K.— “Heterotypical Mitosis in Nereis limbata,” ‘Biol. 
Bull.,’ xiii, 1907, p. 57. 
“ Cliromosomen Studien : III,” ‘ Arch. f. Zellforsch.,’ vi, 
1911, p. 190. 
10a. 
