Thirty-three treatments were carried out.
The fluid infused was normal saline at body tem-
perature, 250 ml. for ponies and 500 ml. for
Thoroughbreds. The method of infusion was to di-
late the cervix with the finger and then to pass
the catheter along the cervix into the uterus.
The saline was infused by gravity from a litre
flask (in which it had been sterilised by boiling),
with plastic tubing connecting the flask to the
catheter. Most of the fluid was retained in the
uterus; reflux was prevented by sealing the
cervix with the fingers for two minutes.

After the treatment daily gynaecological
examinations were made when the size of all pal-
pable follicles and of young corpora lutea were
recorded; 1in addition, each animal was tested
for heat, using a vasectomised stallion, or entire
male fitted with a condom.

RESULTS

A. Anoestrous Mares. Oestrous response depended
on the time of year. Thus heat followed infusions
in late February, March, April and October, but
did not follow in November, December, January and
early February. Where oestrus was induced
variable follicle development occurred but in no
case did ovulation ensue; the follicles which had
grown after treatment subsequently underwent
atresia. Where oestrus was not induced there was
little or no follicle development.

B. Dioestrous Mares. Heat was induced in from 1
to 10 days after the infusion, average 3.7 days,
and ovulation followed, an average of 9.1 days
after infusion.

C. Oestrous Mares. The duration of heat and time
of ovulation were not affected by infusion during
heat.

15 Pseudo—Eregnant Mare. A mare which had con-

ceived suffered embryonic resorption between 32 and
52 days of pregnancy. This was followed by pseudo-
pregnancy. She was infused 64 days after

ovulation and came into heat three days later.