TRANSACTIONS OF SECTION D. 521 
9. A Case of Unilateral Development of Secondary Male Characters in 
a Pheasant; with Remarks on the Influence of Hormones in the 
Production of Secondary Sex Characters. By C. I. Bonn. 
Description of Specimen. 
The specimen shown is the skin of the White Ringed Formosan variety of 
the Chinese Pheasant. 
The plumage on the left side is roughly that of the adult male. The left leg 
shows a well-marked spur. This is absent in the right leg. 
The white-ringed neck feathers occur in a unilateral half-circle on the left 
side only. 
The wing primaries and coverts are female in character with the exception 
of a few male feathers on the left side. 
The tail coverts are of the male type. 
The tail feathers (rectrices) show a unilateral assumption of the male 
pigmentary pattern on the uncovered side of each feather, there being no 
limitation of male plumage to the left side of the tail as a whole. 
Examination of the Internal Organs. 
A well-developed oviduct is present on the left side, and a sex organ occupies 
the usual situation of the left ovary. 
Microscopic sections of different areas of this gland show that it is an ovi- 
testis. It consists of ovarian elements undergoing pigmentary degeneration and 
of testicular elements which show active growth. 
This case presents a difficulty if we accept the ordinary or hormonic explana- 
tion of the origin of secondary sex characters. 
Consideration of the following facts :— 
(a) That the gradual destruction of ovarian tissue by disease or new growth 
in young individuals of the human species and birds is more frequently 
associated with the assumption of secondary male characters than the removal 
of the ovaries by castration. 
(6) That islands of actively growing male elements can frequently be found 
in the degenerating ovaries of female individual birds which have assumed male 
characters. 
(c) That secondary (male) sex characters can be arranged in groups which 
vary in the extent to which they are dependent on the internal secretion of the 
corresponding sex gland. 
(d) The occurrence of hermaphrodite individuals in which the (somatic) 
secondary sex characters correspond with the constitution of the primary sex 
gland on the same side of the body. 
All these facts suggest that two factors at least are concerned in the origin 
and development of secondary sex characters: one, a gametic factor—the 
primary sex gland, and the other a somatic factor. These two factors may 
vary independently of each other under certain conditions of abnormal here- 
ditary transmission. 
Analogy between the ‘hormonic’ theory of the origin of secondary sex 
characters, and the ‘ gametic factor’ theory of the origin of ‘unit’ characters 
in the zygote. 
10. Experiments on the Metamorphosis of the Azolotl. 
By E. G. BoutEncer. 
11. The Morphology of the Mammalian Tonsil. 
By Miss M. L. Herr, B.Sc. 
Tonsils are normally present in most of the mammalian orders, and do not 
atrophy till extreme old age, except in man. Though the physiological import- 
ance of the tonsil is at present undetermined, it has every appearance of a healthy 
