254 Regulating the Sex of the Offspring of Animals. 
each trial. I can consequently declare that I consider Professor 
Thury's system to be real and certain, and 1 hope that all 
breeders will speedily profit by it. 
" Drawn up at Montet, February 10, 1863. 
" (Signed), G. Cornaz.'* 
We may learn from a pamphlet of Professor Thury, ' On 
the Law which regulates the Sex of Plants and Animals,' what 
is his scientific theory, and what are the practical directions 
which he deduces from it. 
The following statement is a brief summary of his views. 
Starting with the vegetable kingdom, Professor Thury adopts 
the theory of Knight, who, in concert with Wolff, De Candolle, 
and Robert Brown, considered stamens and pistils to be funda- 
mentally identical (both being modifications of the leaf), and 
further regarded the production of the male organ in plants as 
due to greater maturity or more perfect development. 
Considering how general the laws of Nature are, the Pro- 
fessor infers that the propagation of animals follows an ana- 
logous course. He states that it has already been admitted 
that for certain oviparous animals the last hatchings produce 
males ; that Huber recognized as fact that early fecundation 
produces female bees, and vice versa ; and so from one step to 
another he arrives at the conclusion that an egg yet unimpreg- 
nated, is female during the first part of its passage down to the 
matrix, and male in the last part. The sex, then, of the creature 
will depend on the degree to which the egg is matured at the 
moment of fecundation. He therefore considers it to be a 
general law that fecundation which follows shortly after " heat " 
or menstruation breeds female offspring, and vice versa. 
The following are his directions and cautions : — 
1. The peculiarities of different cows should be observed and 
taken into account. The number of hours during which they 
take the bull varies from 24 to 48. To obtain a heifer, the 
first part of this period is selected ; for a bull-calf, the latter 
part. 
Exceptional animals, s"uch as are fat or tied-up, afford no fair 
criterion ; but healthy, well-conditioned specimens, living in 
the open air, should be selected for experiment. 
These views must only be taken for what they are worth ; so 
far as the result depends on the mother, and she is a fair repre- 
sentative of her sex, the hint may be serviceable ; but that the 
sex of the offspring is quite independent of the sire, as is here 
assumed, is a doctrine which will not pass unchallenged. 
