G50 
GILBERT E. JOUNSOX. 
been devised, b}' wliicli tlie natui’al food is conveyed in a 
nutritious form, convenient for cultural purposes. 
(5) The nematodes removed from the freshly killed worm 
and reared in cultures, or obtained from the dead worm 
decaying under natural conditions, develop into males and 
females. Subsequent generations, however, bred under cul- 
tural conditions, consist in almost all cases of females only. 
(6) Examination of these cultures, consisting of females 
only, reveals the fact that they are in reality hermaphrodite. 
(7) Reproduction is frequentl}’ — perhaps always — herma- 
phroditic. But cases occur in which it appears to be bisexual 
— that is to say, both hermaphrodites and true females may 
exist side by side in the same species, as in Rhabditis 
marionis Maupas. 
No ^'partial hermaphrodites” have been found, nor have 
any cases of “ re-fertilisation ” been observed. 
(8) The numerical ratio of males to females is extra- 
ordinarily variable, and no rule governing the fluctuations 
has yet been found. 
(9) I have not been able to follow out the life-history in its 
entirety, but evidence is affoi’ded of the probable mode of 
transmission and of infection. 
Birmingham, 
November 26tli, 1912. 
Bibliography. • 
This bibliography includes only those works which are actually men- 
tioned in the text of my paper. 
1. Schneider, Anton. — ‘ Monographie der Nematoden,’ Berlin. 1866, 
p. 154. 
2. Bastian. H. C. — “ Monograph of the AnguiUulidae,” ‘ Trans. Linn. 
Soc. Lond.,’ vol. xxv, London, 1865, p. 77. 
3. Von Linstow. — “ Helminthologische Studien,” ‘Archiv fiir Natur- 
geschichte,’ Jahr. 48, Bd. i, Berlin, 1882, p. 15. 
4. Lankester, E. R. — “ Anatomy of the Earthworm,” Part 1, ‘ Quart. 
Journ. Micr. Sci.,’ 1864, p. 260. 
