NO. l6 DUCTLESS GLANDS OF THE ALLIGATOR REESE 5 



to see any great difference between them, or to determine where one 

 organ ends and the other begins. 



In the small amount of alligator material examined, no vesicles of 

 large size were present and no colloid was seen. Figure 7 (pi. i) 

 represents a portion of the organ under consideration as seen under 

 moderately high magnification. The fairly distinct capsule (c) is 

 continuous with the capsule of the thyroid gland. The main body or 

 stroma is composed of a very indefinite, finely granular material, the 

 structure of which is very difficult to determine. It stains with eosin, 

 and contains scattered nuclei which stain deeply and are smaller and 

 more irregular than the nuclei in the thyroid. This material in places 

 gives the impression of irregular, indistinct cells ; in other places it 

 has almost a fibrous appearance. Numerous irregular spaces are seen 

 in it. 



The two characteristic structures of this organ are the degenerate 

 alveoli, and the structures that Vincent calls " Hassall's corpuscles " 

 from their resemblance to that characteristic feature of the thymus 

 gland. 



The alveoli (fig. 7, a) are small and under low magnification have 

 the appearance of thick-walled blood vessels. Under higher magni- 

 fication the alveoli have the appearance of being in different stages 

 of degeneration, although whether this is really so the writer is not 

 prepared to say. The alveolus figured has a thick granular wall in 

 which two sets of small, irregular nuclei are scattered, and in which 

 no indication of transverse cell walls is seen. One set of oval or 

 spherical nuclei lies close to the lumen, into which many of the nuclei 

 project. The other nuclei form an indistinct layer around the pe- 

 riphery of the alveolar wall. 



Surrounding these structures is a fairly distinct layer of dense 

 material resembling fibrous connective tissue ; this is one reason for 

 the resemblance of the alveolus to a blood vessel noted above. The 

 resemblance of these alveoli to degenerate alveoli of the thyroid 

 would lend support to the view, held by some, that the alveoli of the 

 two glands are the same. 



The other structures, the so-called " Hassall's concentric corpus- 

 cles " (he) are small collections of nuclei, mostly spindlelike or cres- 

 centic in shape, that are arranged in concentric circles very much as 

 in the true Hassall's corpuscles of the thymus gland. No empty space 

 is seen in the corpuscle, the center of the circle being occupied by a 

 group of small, round nuclei. Besides these concentric groups, other 

 smaller groups of nuclei are seen which do not show any concentric 



