SECTIONAL TRANSACTIONS.—D. 321 
her own father, produced two yellow Q kittens and one ¢ which was yellow with 
a few flecks of black. When mated to an unrelated yellow 3, she produced all yellow 
kittens of both sexes. From the result of these two matings it is possible that this 
female is either a genotypic tortoiseshell or a yellow which, by a process of partial 
non-disjunction has, carried away a small portion of a chromosome bearing black 
adhering to one of those bearing yellow. If this were the case, it would prove the 
sex-linkage of both black and yellow. 
12. Mr. C. C. HentscHEt.—On the Correlation of the Life-history of the 
Acephaline Gregarine, Gonospora, with the Sexual Cycle of the Host. 
The life-history of the acephaline gregarine, Gonospora varia, is shown to be very 
closely bound up with the sexual cycle of its host, Audowinia (Cirratulus) tentaculata. 
The parasites live in the coelom among the developing genital products of the worm, 
and complete their life-history contemporaneously with the growth and maturation 
of the gametes. Thus the gregarines are small in the autumn, when the reproductive 
cells are only slightly developed, but grow during the winter, forming in the summer 
spores which are presumably shed with the worm’s genital products, when re-infection 
probably takes place and the cycle recommences. Occasionally, gregarines are 
found in segments containing no reproductive organs. In these circumstances, they 
cannot complete their proper life-history, but remain stunted and unable to form spores, 
often causing, apparently, some pathological effect on the host. It would appear, 
then, that the gregarines cannot develop properly except in the presence of the gonads. 
It seems as though some substance may be formed that is essential for their growth, 
and which may be closely connected with the ovaries or testes, if not actually secreted 
by them. 
AFTERNOON. 
13. Mr. M. A. C. Hinron.—The Dentition of the Pigs, with special 
reference to the Cheek-teeth of the Wart Hog (Phacocherus). 
In several genera of pigs there is a tendency for m$ to become larger and later in 
eruption. A late Pliocene member of the Sus scrofa group has m8 in full wear at a 
moment when m} still retain much of their crown structure; but most modern 
species do not cut m3 until m} have been worn down to stumps. 
In Phacocherus, m3 are very large and complex. Though described as per- 
sistently growing, they are, in fact, of limited though long growth; in old age their 
pulps fail, and they develop very peculiar fangs. A large anterior fang, recalling that 
of m3 in Elephas, is formed long before growth ceases behind. This continued growth 
_ of its hinder part causes each m, to rotate in a vertical plane so that the posterior 
end of the tooth describes an arc whose centre lies in the neighbourhood of the anterior 
fang. Progressively the crown is cut more and more obliquely by the plane of wear ; 
the discs of wear, circular in the beginning, become long ellipses, and the whole tooth 
becomes much longer from before backwards (measured at the grinding surface). 
While these changes are taking place in m3, m}, m? and p$ are worn out and shed, 
the places of m} and m2 being usurped by m3, which slowly slide forwards, so that, as 
already described by Owen, m$ come to abut against p¢; finally the last-named teeth 
are shed, and m# alone remain. In extreme age the growth ceases in the hinder part of 
m3, thin roots are developed, and, in order to bring the last remnants of the crowns 
above the gum, the alveolar margins of the jaw-bones are lowered by absorption 
of bone. 
14, Dr. P. Scumrpr.—The Breathing-apparatus of Flatfishes. 
15. Dr. A. J. Grove and Mr. L. F. Cowtry.—Coition and Cocoon 
Deposition in the Brandling Worm (Eisenia fotida (Savigny)). 
Miss K. Foot (Journ. of Morph., vol. 14, p. 483) states, in her description of coition 
in the Brandling, that both cocoons are formed while the worms are united, and when 
they separate each deposits a cocoon encased in a moiety of the slime tube. By the 
development of special means of observation it has been possible to watch the process 
of coition, and also of cocoon deposition under a binocular microscope. In the 
former, no evidence was observed of cocoon formation, and the slime tube, secured 
1925 V 
