192 Trans. Acad. Set. of St. Louis. 



and sometimes, but rarely so, near the nasal edge of the tarsus 

 (Fig. 32). While, as a rule, they are situated between the 

 apex of the Meibomian glands and the upper (in the lower 

 eyelid the lower) edge of the tarsus, they are not at all in- 

 frequently found to reach in between the Meibomian glands 

 and as far down (or up) almost as the orifices of these 

 glands at the lidmargin (Figs. 32 to 35). 



The histological structure of these glands is also of the 

 acinous type, and they do not essentially differ from the 

 lacrymal glands, although their appearance and general ar- 

 rangement are slightly modified by the dense tissue in which 

 they lie embedded (Figs. 36, 37). Their lobules are 

 formed of numerous round and oval acini which consist of a 

 basal membrane lined with cylindrical (conical) cells arranged 

 around a central lumen, with a round or oval nucleus near 

 their base. The small excretory ducts coming from the acini 

 unite into a larger one which is sometimes quite long and to 

 which smaller acini are attached throughout its length, the 

 small ducts of which empty directly into this large duct 

 formed by the union of the ducts coming from the most dis- 

 tant acini. It is probably this arrangement which has led to 

 their being named ** acino-tubular " glands. Sometimes, 

 however, and especially when these glands are situated be- 

 tween the Meibomian glands, this excretory duct is but very 

 short. The excretory ducts of the aci no-tubular glands are, 

 also, lined with cylindrical epithelium, like those of the 

 lacrymal glands. Their external orifice lies in the palpebral 

 conjunctiva (Figs. 35, 38). 



These acino-tubular glands are generally spoken of as muci- 

 parous glands. For what reason, I have been unable to deter- 

 mine, and it is not possible to examine their secretion chemi- 

 cally. Their structure as stated, with the slight modification due 

 to density of the tissue in which they lie embedded, corresponds 

 in every respect with the lacrymal glands. The microscopi- 

 cal staining reagents which seem to have a special affinity to 

 mucous substances, as haematoxylin, Bismark-brown, and 

 others, do not stain any part of these glands in particular. 

 Now and then I have found a concretion in the excretory duct 

 of such a gland, but this cannot be taken as proof of their 



