4 P. J. P. Barrington, 



giving the reactions of mucin and (ii) as a homogeneous, gelatinous 

 looking mass, which did not give the reactions of mucin, but retained 

 the iron haematoxylin stain with some tenacity . These two substances 

 were quite distinct, no intermediate stages between them ever occurred 

 though mixtures of the two in the same acinus were frequently seen. 

 Those acini formed of the columnar mucinous cells most frequently con- 

 tained mucin, while the homogeneous substance was usually seen in 

 dilated acini formed of short cells with httle or no mucin. In a few in- 

 stances, however, mucinous secretion occurred in acini whose sections 

 showed no cells giving a mucin reaction, and conversely homogeneous 

 secretion occurred acini the sections of which showed all the cells giving 

 a mucin reaction. When, as commonly occurred, both kinds of secretion 

 were found in the same lumen, the homogeneous kind usually formed 

 a mass in the centre, and surrounding this and next the cells was a layer 

 of the mucinous network, sometimes small islets of mucin were seen 

 in the homogeneous mass, and lastly, where a large amount of mucin 

 was present in the acini, islets of the homogeneous substance were pre- 

 sent in the mucinous network. Both kinds of secretion were seen in the 

 ducts, but when these were greatly distended, it was always either with 

 mucin alone, or a mixture of the two containing large proportions of 

 mucin: from this it may be inferred that when the gland is normally 

 secreting fast the secretion leaving it is chiefly mucin. The cells of 

 such rapidly secreting glands nearly all contained a certain amount of 

 mucin, so from this fact it is impossible to say, whether the homogeneous 

 secretion is secreted by the cells when they are in a more or less non- 

 mucinous state, or whether it is due to a chemical alteration in the 

 mucin after secretion, which takes some time to occur. 



In addition to these two forms of secretion, desquammated cells 

 were occasionally seen in the ducts and more rarely in the acini. 



A considerable number of glands taken from cats which were 

 neither pregnant nor lactating were examined, pregnancy being as- 

 sumed absent when there were no localised swellings of the uterine 

 cornua. It was found that they varied very greatly in the amount of 

 mucin they contained in their cells. They could be roughly divided 

 into two classes, (i) those in which about half or more of the cells seen 



