176 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Degeneration of Pelvis in Female Gopher. — F. L. Hisaw ( Proc . 
Amer. Soc. Zool. in Anat. Record, 1922, 23 , 108). In mature females 
of Geomys bursaria the pubic bones are completely ossified and there is 
a pubic symphysis. In both sexes the pelvic girdles are greatly reduced 
in size — an adaptation to the fossorial habit. But the pubo-ischiatic 
vacuity is too small for the birth of the young. During the 
breeding season, however, a degeneration of the pelvis of the young 
female sets in, beginning in the pubic region and continuing almost to 
the obturator foramen. After the birth of the young, the symphysis is 
not re-formed, and virgins may be distinguished in this way from old 
females. Females which are abnormal in their reproduction or are 
confined in cages retain the closed symphysis. The degeneration in the 
pelvis seems to be due to internal secretions of the reproductive system, 
either before or during pregnancy. J. A. T. 
Hen-Feathering induced in Male Fowls by Feeding Thyroid.— 
Benjamin Horning and Harry Beal Torrey {Amer. Soc. Zool. in 
Anat. Record , 1922, 23 , 132). Fed daily with thyroid, male Bhode 
Island Red chicks developed female plumage, although males of this breed 
do not ordinarily pass through a stage of female plumage. The plumage 
of capons, usually ultra male, is not affected ; nor are castrated females. 
There seems to be an increase in the activity of the “ lutear ” interstitial 
tissue of the testis. J. A. T. 
Photic Reactions of Tadpoles. — Vasil Obreshkove {Journ. Exjper. 
Zool., 1921, 34 , 235-79, 9 figs.). There is an optimum intensity for 
the responses of Rana clamitans tadpoles to light. At and below 
0*3 candle-metre intensity, the light ceases to have a physiological 
effect, regardless of the time of exposure. With effective light inten- 
sities below 20 candle-metres, the changes in the receptors during 
illumination proceed according to the Bunsen-Roscoe law. That is to 
say, the time required for a given change varied in inverse proportion 
to the intensity of the light. With intensities higher than 20 candle- 
metres, a deviation occurs in the intensity-time products, which seem to 
proceed with a definite constancy. Nearly the whole of the reaction- 
time in Rana clamitans represents a sensitization period. The eyes are 
not necessary for the responses of tadpoles to light of the kind used in 
these experiments. Tadpoles subjected to continuous illumination of 
definite duration become no longer sensitive to light. In the process of 
fatigue, the reaction- time at any moment has a definite relation to 
previous illumination. Photosensory recovery after complete exhaus- 
tion occurs in the dark in about fifty minutes. J. A. T. 
Penetrative Capacity of Ultra-violet Rays in Frog Embryos. — 
W. M. Baldwin {Anat. Record , 1921, 21 , 323-7). Developing 
embryos were exposed at the time of the closure of the neural tube. 
Microscopic examination of the sections showed that the ultra-violet 
light rays produced an injury which was wholly confined to the two- 
layered ectoderm of the embryo. The underlying mesoderm cells were 
quite normal. The protecting screen of ectoderm was only about 
0 * 02 mm. thick. A slight increase in the time of exposure or in the 
