ROBERT RUSSELL BENSLEY 25 



which was identified as Macallum's prozymogen. In this study it was shown that the 

 prozymogen of the base of the cell increases and diminishes in amount pari passu 

 with the diminution and increase respectively of the zymogen granules, and it was 

 therefore regarded as an antecedent substance of the latter. The occurrence of similar 

 substances in the basal zones of the serous cells of the glands of von Ebner and of the 

 oesophageal glands of the frog was also described, and it was suggested that the basal 

 filaments of Solger and Erik Mtiller were of a similar nature. 



Since the publication of this paper, the presence of so-called basal filaments has 

 been demonstrated in a host of serous cells from various sources by Zimmermann 

 (1898), Gamier (1900), Theohari (1899), Cade (1901), and others. The three last 

 mentioned accept in a modified form the interpretation of the writer that the so-called 

 basal filaments contain the antecedent substance of the zymogen granules a concep- 

 tion which was also adopted by Solger (1899) for his basal filaments of the sub- 

 maxillary gland of man. 



It is clear from the foregoing that the dark-staining cells of the rabbit's glands 

 of Brunner agree with serous cells of many other glands in containing large quantities 

 of prozymogen in their outer zones and in containing in their inner zones granules, 

 visible on the fresh cell, of a phosphorus-holding substance, presumably some sort of 

 zymogen. This fact should speedily lead to a chemical examination of the glands of 

 Brunner from this animal to determine the nature of the secretion of these cells. On 

 anatomical and microchemical grounds, there would appear to be a stronger possibility 

 of a positive result in the search for important digestive ferments in the glands of 

 Brunner of this animal than in those of any other mammal. 



The conclusion that the dark cells of the glands of Brunner of the rabbit are 

 serous cells is further borne out by the negative evidence afforded by staining in 

 muchaematein and mucicarmine, in which the secretion granules of these cells remain 

 absolutely colorless. 



The facts in connection with the glands of Brunner of the rabbit may be summed 

 up as follows : The glands of Brunner of the rabbit are mixed glands (well compared 

 by Castellant to the mixed glands of the trachea) composed of mucous portions, the 

 cells of which stain strongly in muchaematein, mucicarmine, etc. ; and serous portions, 

 which do not stain in these solutions, but on the contrary possess a basal zone with 

 indistinct radial striation containing a large amount of prozymogen, which may be 

 demonstrated by the microchemical reactions for iron and phosphorus, and an apical 

 zone in which minute granules, presumably of zymogen, are to be seen. These two 

 types of cell are morphologically and chemically distinct from one another, and no 

 intermediate types are to be found. 



The pyloric glands of the rabbit are very similar to those of the glands of 

 Brunner, but the former, as Dekhuyzen (1888) pointed out, are, as a rule, smaller and 

 contain more cytoplasm and less secretion than the latter. However, by selecting an 

 animal that has been fasting for some time, pyloric glands may be obtained the cells of 



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