XX II I.] THE SALIVARY GLANDS. 259 



(iv.) Harden other pieces in Flemming's mixture, and stain "in 

 bulk " in borax-carmine as in (ii.). 



(v.) Heidenhain's Method. 1 This method is also applicable 

 to the pancreas. Small pieces of glands e.g., sub-maxillary of 

 guinea-pig, dog, and cat hardened in alcohol (ii.) are placed in 10 

 cc. of 0.5-1 per cent, watery solution of hsematoxylin (6-8 hours); 

 and then for an equal period in 0.5-1 per cent, potassic bichromate, 

 or i per cent, watery solution of alum, or stain with .3 per cent, 

 hsematoxylin (distilled water to be used), and differentiate with I 

 per cent, neutral chromate of potash, which forms a steel-grey 

 compound with haeniatoxyliii (p. 70). The stain does best with 

 objects hardened in alcohol or picric acid. The pieces are quite 

 black when removed from the second fluid. In this method, the 

 union of the reagents takes place in the tissue itself. The nuclei 

 are bluish-black, the cell-substance a steel-grey, while the demilunes 

 .stand out distinctly. This is an excellent method for these glands. 

 Cut in paraffin. 



(vi.) Mucous glands harden well in picric acid. 



My experience leads me to believe that in studying a mucous 

 salivary gland, it is best to begin with one whose acini contain only 

 mucous cells and no demilunes. Such glands are the sub-lingual 

 of a guinea-pig and sub-maxillary gland of the mole. Then proceed 

 to the sub-maxillary of a dog, which has demilunes at intervals, 

 and lastly, take the acini of a cat's sub-maxillary, where the demi- 

 lunes form a nearly complete layer outside the true mucous cells. 



In order to obtain a general view of the origin of the ducts from 

 the acini of the lobules, and the union of small lobular ducts to 

 form larger ducts, it is well to examine a preparation of the salivary 

 glands of the cockroach, which can be removed en masse (p. 265). 



1. Sub-Lingual Gland of Guinea-Pig. This shows acini lined with 

 mucous cells iviihout demilunes (L and H). Note the acini, each lined 

 by a single layer of clear transparent mucous cells, resting directly 

 upon a basement membrane without the intervention of any demi- 

 lunes. In the arrangement of capsule, septa, and ducts, it resembles 

 the salivary glands of the dog. The gland is like fig. 249 without 

 the demilunes. 



2. Sub-Maxillary Gland of Dog. (a.) (L) Observe the capsule, 

 which sends off thin connective-tissue septa into the gland, mapping 

 it out in polygonal lobes, which are further subdivided by finer 

 septa into lobules. In the larger septa, sections of blood-vessels and 

 gland-ducts (lig. 249). 



(/>.) Within each lobule aggregations of acini or alveoli, which 

 make up the smaller lobules. The shape of the lobule depends on 

 the way it has been cut. Branches of the finer gland-ducts few 

 1 Archivf. mik. Anat., 1884, p. 468, and 1886, p. 383. 



