24 EXTRACTS FROM " THE THEORY OF MENSTRUATION.” 
the catamenia continue four or five days, but, in general “not more 
than twenty -four hours, and at other times not more than five or 
six.” 
When the animal, as in London, is from one year’s end to the 
other kept within doors, the discharge in many cases may be ex- 
pected to a day : out of doors, although it be prolonged in duration, 
the discharge is less exact in periodicity. 
I have notes of several animals in which I had an opportunity of 
watching this periodic secretion. They were all taken from cows 
during lactation, and therefore at a time when the secretion, as in 
other animals, might least of all have been expected to have been 
periodic. In some examples it was not so ; in others the general 
indications of the oestrum appeared at the usual period, but with- 
out the secretion ; however, in general, the secretion was regu- 
lar. I was not able to trace in any one individual the periodicity 
more than three times ; for the sexual appetite returning so regu- 
larly, and interfering with the secretion of milk, it was found ne- 
cessary to have it gratified. For illustration, one example may 
suffice. 
A cow was delivered in the third week of May; on the 5 th of 
August she was noticed to have a discharge of a sanguineous 
nature proceeding from the vagina. The discharge was preceded 
by the restlessness, starting, and bellowing, with swelling of the ex- 
ternal parts of generation, indicative of the periodic heat in the 
animal. These symptoms passed off in a few hours after the ap- 
pearance of the secretion. On the 27th of the same month, after 
premonitory symptoms similar to those described, a discharge of a 
similar nature was evacuated : in quantity it might be about two 
ounces. On the 16th of September indications of the return of the 
catamenia were made manifest in the conduct of the animal. On this 
occasion steps were taken to gratify the sexual appetite. The result 
of the intercourse that took place was, that the secretion on the ex- 
pected day did not re-appear, and that the animal, evidently from 
subsequent symptoms, had been then impregnated. I had about half 
an ounce of the secretion collected. It had the usual external indica- 
tions of blood : the coagulum that was formed was firm. The fluid 
had the odour peculiar to the cow, strongly marked. The taste was 
saline and mawkish, like blood. Microscopic investigation of this 
discharge left no doubt in the mind in respect to its sanguinity. 
It possessed in it abundance of corpuscles of the same size and 
character as those visible in the blood of the animal. 
Dr. Day thus describes the chemical characters of the clot I was 
able to procure : — 
" I received thirty-six grains of the secretion, which in its physical 
characters resembled ordinary clotted blood. There was no serous 
