274 The Duets of the Human SubmaxiUary Gland 



adjacent lobules are pressed in close apposition, and yet, as a general 

 rule, the attachment between them consists simply of a few fine fibrils of 

 reticulum (Fig. 8). In its early stages, the organ in pigs, as a whole, 

 is regularly symmetrical and the future ducts, marked by the growing 

 columns of cells, branch with great regularity, the larger divisions alter- 

 nately passing first to one side and then to the other of the gland. They 

 can be followed with some distinctness in ordinary sections but in in- 

 jected specimens better results are obtained when the gland is divided 

 and viewed with the stereoscopic microscope which shows these relations 

 in three dimensions. In the simplest forms the blood-vessels form a fine 

 plexus about these growing columns of cells and, as they develop and 

 ramify, the arteries and vessels supplying them follow the same line of 

 growth so that we have an artery and veins developing with each branch 

 of the duct. 



It has been shown '' that the intrinsic vessels of an organ indicate in 

 general the paths along which the different parts of that organ have 

 developed, a principle which is expressed in the following paraphrase 

 of a well-known scientific aphorism, viz. : the angiology of an organ in a 

 measure recapitulates its ontogeny. In the case of the submaxillary this 

 principle obtains and the blood-vessels of the organ represent the lines 

 of its development. Therefore, in injected preparations of the develop- 

 ing gland we can follow accurately the course of the ducts from the 

 vessels that always accompany them. Were it essential, this relation 

 of the blood-vessels to the ducts Avould afford another proof that the 

 ducts themselves also form a record of the development of the gland. 

 It follows, therefoie, that the youngest parts of the organ are the ter- 

 minals of the ducts or alveoli while the oldest portion is the main duct 

 itself. It is also apparent that this relationship of the ducts and vessels 

 gives rise to the invariable conditions observed in the interlobular 

 Spaces where an artery and its venge comites accompany every duct. So 

 constant and regular is this condition that these vessels may be justly 

 termed the vasa comites of the ducts. In embryo pigs the Gl. submaxil- 

 laris in gross appearance is a small opalescent organ lying near the 

 angle of the mandible covered by the developing platysma and fascia. 

 At this stage it is not situated in a fossa, nor is it jammed up beneath 

 the mandible. From the earliest period that it can be distinctly seen 

 with the naked eye it is reniform in shape and perfectly symmetrical; 



^ Flint : ^lonograph on the Adrenal. Contributions to the Science of Medicine, 

 dedicated to Dr. William H. Welch by his Pupils. Johns Hopkins Hospital Reports, 

 Vol. ix, Baltimore, 1900. 



