During the course of the main investigation the following observations were made on some other aspects of reproduction in the sow.
An examination of the reproductive tract of sows killed at slaughterhouses in East Anglia showed a high percentage of cystic abnormalities in the ovaries (Perry & Pomeroy, 1956). However, the sample of sows necessarily excluded any gilts, so an examination has been made of the incidence of ovarian abnormalities in post-pubertal gilts at two bacon factories. The ovaries of 273 gilts were examined and divided into (a) ovaries containing corpora lutea, (b) ovaries not containing corpora lutea. These were then further classified as normal or abnormal. The chief criteria of abnormality were the presence of cystic follicles, i.e. of greater than ovulatory size (10 mm. in diameter) or cystic corpora lutea, i.e. large flabby corpora lutea with hollow centres. Gilts with numerous haemorrhagic follicles in the ovaries were also classified as abnormal, but it is quite possible that this condition is a common occurrence in gilts just before puberty. However, rather than underestimate the incidence of abnormalities these ovaries were classified as abnormal.