266 Mr. Walter Heape. Ovulation and [ Mar. 6, 
activity of the whole generative system is not in the ovary, that organ is 
at least essential to the normal functions of the remainder of the system. 
In the same way excision of the generative glands affects, for instance, the 
growth of horns in the male, and exercises influence in various ways on 
other organs of the body of both sexes. Thus these organs are probably 
essential to the normal development of sexual characteristics. 
There would seem to be little room for doubt that this is the case. 
But in all animals which have a special breeding season, the ovary has a 
quiescent period, so far as the development of the ova are concerned, 
varying in accordance with the length of the interbreeding seasons. For 
some time before the advent of the sexual season, however, with the probable 
exception of bats, the ovary exhibits activity, and is obviously engaged in 
transmitting nutriment to the ova, which now begin to develop. The 
commencement of this active season is marked by the increased vascularity 
of the gland. The fact that this ovarian activity precedes the sexual season 
is not unfavourable to the view that it exercises influence on the latter. 
It must be recollected, however, that monkeys, although they menstruate 
regularly each month throughout the year, have a subscribed breeding 
season, and their regular menstrual function goes on during the time when 
the ovary is quiescent. Moreover, as ovulation in the bat may take place 
many months after the sexual season is over, and the bat’s ovary is certainly 
quiescent during those intervening months, it may be expected that the 
sexual season in bats occurs in the absence of ovarian activity. Finally, 
it is quite clear that ovulation and procestrum are not necessarily coincident 
in many animals. | 
If these facts are true, it does not seem possible to accept the view that 
the stimulus which induces procestrum and cestrus has its origin in the ovary. 
There is another point to be considered, namely, that the advent of sexual 
activity may be hastened or delayed or, perhaps, prevented altogether ; the 
severity of procestrum and cestrus augmented or reduced; and the ratio of 
fertility influenced, by climatic conditions and food. 
Similar conditions obtain and similar results follow in the male. 
Generative Ferment and “ Gonadin.”—My belief is that the stimulus which 
primarily induces such activity is of extraneous origin; that it 1s due toa 
change in the constitution of the blood, brought about by climatic influences 
and food, which from the nature of its growth would seem to be always 
specially nutritious at this season; that it results in increased vitality 
throughout the body—clearly evidenced by the growth of horns, wattles, 
and other excrescences, by the growth of hair and plumage, and the 
accession of brilliant colouring to such epidermic growths or to the skin 
itself—and similarly affects the generative system. 
