8UPRA.RENAL CAPSULES. 



835 



granular substance is also present. Clear spots 

 may also he seen glimmering from amidst 

 the contents of the gland, and isolation shows 

 these to be cells of 5 to 9-1000ths of a line 

 in diameter, with finely granular contents and 

 a nucleus. The application of water renders 

 this more visible. Part of these cells arc de- 

 void of the cell membrane, but others of 

 them exhibit it very distinctly. Besides these, 

 free nuclei are found ; these are sometimes 

 vesicular and contain a nucleolus, sometimes 

 they appear to be granulated. The nuclei 

 which are included in cells are always of the 

 latter kind. 



From these microscopic characters of their 

 contents exactly corresponding with those of 

 the higher Vertebrata, the import of these 

 organs as supra-renal capsules is placed be- 

 yond all doubt. 



The same structure obtains in the tailed 

 Batrachians, only the nuclei and cells are 

 larger, while a part of the latter are com- 

 pletely enclosed in fat. Numerous branches 

 of the afferent renal veins break up anew in 

 the supra-renal capsules, in order to provide 

 it with venous blood, a condition which re- 

 minds us of that seen in the Snakes. 



The minute anatomy of the supra-renal cap- 

 sules of Fishes is very similar. In the Salmon 

 Ecker found them consisting of separate lo- 

 bules, which are deposited in a loose areolar 

 tissue perforated by vessels, and which, in ad- 

 dition, receive a special covering of this areo- 

 lar tissue. Each lobule is composed of a 

 number of large gland-vesicles, from 5 to 11- 

 lOOths of a line in size, which are surrounded 

 by blood-vessels. Their membrana propria 

 is completely structureless. In their contents 

 we again recognise the pulverulent molecules, 

 separate fatty granules, and vesicular and gra- 

 nular nuclei of 2-1000ths of a line in size. 

 The granular substance is rolled around these 

 nuclei in the manner before described ; so that 

 part of them come to notice as spheres with- 

 out walls, while part are real cells, surrounded 

 by a membrane, and of 7 to 9-lOOths of a line 

 in measurement. It is not unfrequent to find 

 two or three nuclei, instead of one, in their 

 interior. We have remarked an exactly si- 

 milar condition in the supra-renal capsules of 

 the young Pike ; there is the same fibrous 

 coat, giving off* processes which pass into the 

 interior, and thus isolate the gland-vesicles, 

 but the supra-renal organs are less divided 

 into lobules than in the fish previously con- 

 templated. The contents of the gland-vesicles 

 vary according to their size. 



In the supra-renal capsules which are 

 smallest of all, and measure under 9-100ths 

 of a line, there are no gland-vesicles to be 

 seen, but only nuclei : to these we shall im- 

 mediately return. But in supra-renal cap- 

 sules which are somewhat larger, the nuclei 

 are partly included in cells. 



By a yet further enlargement of these or- 

 gans, the gland-vesicles also appear : they 

 contain fine molecules, fatty granules, and 

 nuclei. These are vesicular, flat, of circular 

 irregular form, and vary in size from 22 to 





30-10,000ths of a line. Each of these nuclei 

 contains a single or double nucleolus. Not 

 unfrequently forms appear which may be con- 

 nected with a division of the nucleus, where 

 it appears cut through the middle, or even 

 incompletely broken up into three parts. 



Finally, the gland-vesicles also contain 

 cells. By enlarging, these cells experience a 

 gradual transition into new gland-vesicles, 

 which are contained within the larger ones ; 

 so that we may distinguish them into mother- 

 vesicles and endogenous daughter-vesicles, 

 just as often happens in other cells, to wit, 

 those of cartilage. The endogenous vesicles 

 occur in the older ones in variable numbers. 

 The smaller gland-cells contain only a single 

 nucleus ; others possess two or three of them, 

 which sometimes lie closely packed on each 

 other. Finally, in other cells, three, four, five, 

 and niore nuclei occur ; and in this manner, 

 by an increase in the number of the enclosed 

 nuclei, and at the same time a continual fur- 

 ther extension of the cell membrane, the cells 

 experience a transition into glandular ve- 

 sicles. 



These conditions, which were-first observed 

 by Ecker, and which I can completely con- 

 firm from an examination of the same animal, 

 will quite permit us to conclude as follows 

 regarding the development of the glandular 

 vesicles. [n the smallest gland-vesicles a 

 multiplication of nuclei takes place, most pro- 

 bably from those already present, by the me- 

 thod of fission. This multiplication extends 

 itself to free nuclei, as well as to those which 

 are included in cells. In the latter case, the 

 cell-membrane must be more and more ex- 

 tended by the formation of the nuclei; and in 

 this manner the cells of a gland-vesicle them- 

 selves are changed into new endogenous ve- 

 sicles. By this process, the mother vesicle 

 itself is considerably extended ; so that, finally, 

 its membrane comes into contact with the 

 sheath of the supra-renal capsule. Finally, 

 after the membrane of the mother vesicle 

 is destroyed new areolar tissue seems to be 

 developed between the secondary vesicles. In 

 this way the small supra-renal capsules of the 

 Pike experience their growth. 



In large old Pikes, the process of multipli- 

 cation and growth seems no longer to occur. 

 In their supra-renal capsules, the fibrous 

 foundation is more considerable in quantity, 

 so that by its means the gland-vesicles are 

 more separated from each other. 



So also in the genus Cyprinus, where a pre- 

 cisely similar structure of the supra-renal cap- 

 sules may be observed, one lights upon con- 

 ditions of nuclei in the gland-vesicles which 

 suffice to prove the transition of gland-cells 

 into gland-vesicles. As to the problematical 

 organs of the Myxine and Petromyzon, the 

 glands which Miiller discovered in the Myxi- 

 noid fishes consist of tufts of small elongated 

 lobules, which are clothed with a kind of cylin.- 

 drical epithelium.* Concerning the glands in 



* See the drawing of this glandular structure in 

 J. Miiller's Essay. 



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