238 SUMMARY OF CURRENT RESEARCHES RELATING TO 



female sex-ensemble there is no external vaginal entrance, as it ends in 

 the prostatic sinus. 



Hunter's Freemartin and Reversion.* — D. Berry Hart describes a 

 freemartin which resembled the wild park cattle in having a white hide, 

 black muzzle, black hoofs, blackish spots on the legs, and great timidity. 

 The mother was a normal shorthorn ; the co-twin a normal bull. A 

 typical Hunter's freemartin is a sterile, genitally malformed bull, with 

 small undescended testes and rudimentary epididymes, vasa deferentia. 

 and Mullerian elements. Yesicukeseminales are present. The external 

 genitals consists of labia majora, clitoris, and the urinogenital sinus 

 element (one inch in length) of the vagina. 



The potent bull-calf and the freemartin are produced from one 

 fertilized ovum, but the freemartin has allotted to it the hydatid testis 

 and prostatic utricle normally given to the single bull. This produces 

 an exaggerated simulacrum of the female genital tract. 



The thyroid, thymus, and suprarenals were found to be normal. The 

 internal genitalia showed fatty degeneration, and were represented only 

 by the urinogenital sinus and the epididymes. The skull was normal. 

 The chief point of interest was the (ectodermic) reversion to the wild 

 park cattle type. A theoretical interpretation is given of the way in 

 which this reversion might come about — by retention of certain ancestral 

 chromosomes normally lost in polar-body formation. 



Sex in Pigeons. | — 0. Riddle finds that eggs destined to produce- 

 males are smaller, and have higher water-content and smaller energy- 

 content, than those that produce females. Whether the difference in 

 energy-content (estimated by the use of the bomb calorimeter) is the 

 cause of the difference in the eventual sex, or whether it is induced by 

 a difference in the unfertilized eggs which determines the difference in 

 storage metabolism is uncertain. 



There is reason to believe that there are two kinds of ova, and that 

 those destined to produce males contain a sex-chromosome which the 

 others lack. It may be that the difference in chromosomal content may 

 be the cause of the difference of energy-content. 



When the female pigeon is subjected to alcohol vapour, it lays eggs 

 smaller than the normal. Phloridzin and urotropin reduce the fertility 

 of the egg. 



Whitman found that if certain somewhat distantly related species of 

 pigeons be crossed and their eggs be removed as fast as laid, so as to 

 induce the pair to continue to lay fertile eggs, then in spring both eggs 

 of a clutch will produce males nearly always or epiite exclusively ; the 

 last eggs in autumn will produce females nearly always or epiite ex- 

 clusively ; *while in the transition period the first egg of the clutch 

 usually produces a male and the second a female. It may be that the 

 experience induced a change in the sex-fate of the eggs, or it may be 

 that the distribution of the male and female egg in the ovary is such 



* Edinburgh Med- Journ., March, 1915, pp. 1-7 (1 pi.). 



f Year-bDok, Carnegie Inst. Washington, xiii. (1914) pp. 117-19. 



