
1905. | Degeneration of Ova in the Rabbit. 265 
ova. In the latter case the constitutional capacity of the ova is concerned, 
and while their degeneration may be due to a defective supply of nutriment, 
it may, with no less probability, be inferred that failure to develop is due 
to their incapacity to utilise the nutriment which is supplied and on which 
other neighbouring ova flourish. | 
It is well known that domestic animals and cultivated plants are more 
prone to vary than are the same varieties or species in a wild state. 
De Vries (No. 32) expresses the view that by feeding up the mother-plant 
with manure the offspring are induced to exhibit a greater variation ; that 
by rich or poor treatment of seed-plants greater variation can be produced 
than by selection of seeds; and that the influence of manures on the 
mother-plant is exercised on the seeds she produces. If this be so, any 
increased capacity on the part of the mother to assimilate nutriment of 
different qualities, or to manufacture such material, will enable her to 
produce more widely varying offspring. 
I would suggest then that when young ova degenerate under the condi- 
tions above specified, there is great probability that in such cases the 
degeneration is due to peculiarities in the constitution of those ova, and 
that such ova require special facilities for development; that they give rise 
to, in fact, “sports,” extreme cases of that variation which it is known 
domesticated animals are specially liable to produce. In view of De Vries’ 
observations and the experience of many practical breeders and_horti- 
culturists, it would seem very important that the whole question of the 
effect of various kinds of nutriment upon the developing ovum and embryo 
should be investigated, for it is reasonable to expect that, given the 
requisite quality of nutriment, the power of producing variable offspring 
would be widely extended and the field for the study of variation 
correspondingly enlarged. | 
The Ovary as a Secretory Gland.—Evidence of the part the ovary takes in 
providing the ovum with nutriment demonstrates that it is a secretory gland, 
and it has been urged that ovarian secretion is responsible for much besides 
the growth of the ovum, that it governs, indeed, all activity of the other 
generative organs. | 
The experience of ovariotomists shows that excision of the ovaries has a 
marked effect on procestrum (menstruation—human) and upon the severity | 
of cestrus (mares), and it is claimed, though it appears to me this requires 
confirmation, that destruction of the corpora lutea prevents the gestation 
of the ova which were discharged from the pre-existing Graafian vesicles 
(cf. Nos. 6 and 7). 
These facts would certainly indicate that if the force which controls the 
VOL. LXXVI.—B. T 
