OCCUPATION OF A TABLE AT THE ZOOLOGICAL STATION AT NAPLES. 187 
I am forced to regard as representing the process of conjugation in 
this form. I hope to publish a full account of these stages, together 
with the observations I have made upon the other Intestinal Trypano- 
plasmas—viz., Trypanoplasma congeri from the stomach of the conger, 
and T'rypanoplasma ventriculi (Keysselitz) from Cyclopterus lumpus— 
in a forthcoming paper.’ 
Secondary Sexual Characters in Birds.—Report of the Conmuttee, 
consisting of Professor G, C. Bourne (Chairman), Mr. 
GEOFFREY SMirH (Secretary), Mr. E. 8. Goopricu, Dr. 
W. 'T. Cauman, and Dr. Marerr Tims, appointed to defray 
expenses connected with work on the Inheritance and Develop- 
ment of Secondary Sexual Characters in Birds. (Drawn up 
by the Secretary.) 
EXPERIMENTS and observations on the sexual characters of birds kept 
in my aviaries have been conducted on the following lines :— 
On Conditions determining the Growth and Development of the 
Comb.—Measurements have been made on the combs of nineteen 
control hens and nine experimentally treated birds, to ascertain whether 
the injection of testis-extract into the female had any effect in 
causing the fluctuations in size of the comb of the hen. It was found 
that these fluctuations were independent of the experimental treatment 
and followed on the infiltration of fat into the comb which occurs 
during the egg-laying periods. Histological observations showed that 
the comb of the laying hen differed from that of the cock in containing 
a central core of connective tissue, which becomes loaded with fat at 
the reproductive periods. These results are published in ‘ Q.J.M.5.,’ 
vol. 56, p. 591, and vol. 57, p. 45. 
On the Cause of Sterility in Hybrid Birds.—An attempt was made 
to rear hybrids between the common pheasant and the jungle fowl, 
but the incubation of about sixty eggs resulted in the hatching of a 
single chick, which died owing to a cerebral hernia two days after 
hatching. This chick on dissection proved to be a male, and the 
reproductive organs were in a perfectly normal condition for a chick 
of that age, showing no degenerative or retarded development. Three 
hybrid male pigeons (hybrid between domestic dove and pigeon) were 
obtained from a pigeon-fancier. These birds were kept for about a 
year in my aviaries and were paired with female pigeons successfully, 
and the eggs were incubated in the normal manner by both parents. 
In all cases the eggs were sterile. The three hybrids were killed and 
dissected, and their spermatozoa and testes, which on inspection 
appeared quite normal, were examined histologically. On comparison 
with normal doves and pigeons, it was found that the great majority 
of the spermatozoa of the hybrids were twice the normal size, and this 
abnormality of size was traced to the fact that the second maturation 
division was entirely suppressed. The abnormality was traced further 
back to the first maturation division, where it was found that the 
