420 INVESTIGATION OF THE KIDNEYS. [sect. 190. 



often present a peculiar appearance, exhibiting collapsed flattened cells, and 

 thus resembling vessels. With equal frequency, we also meet with shorter 

 or longer tubes of the membrana propria, which, when they are folded, are 

 not always immediately recognisable. In examining the pyramids, the very 

 numerous vessels are not to be confounded with the Bellinian tubes or their 

 detached epithelium. The connection of the tubules with the Malpighian 

 capsules can be readily found in the kidney of the frog and fish, on care- 

 fully teasing them out ; but, even in mammalia, they will be seldom sought 

 for in vain, when fine sections are examined after being hardened, and more 

 especially when injected preparations are used. The glomeruli themselves 

 may be frequently recognised in their natural condition, but still better after 

 injection. This may be easily done from the arteries with any kind of fine size, 

 and if such an injection is successful, the whole capillary net-work of the cortex 

 and pyramids is also filled ; and then this part of the circulatory apparatus 

 can be very satisfactorily observed on a perpendicular section. It is also 

 well to examine kidneys injected from the veins, in which only the capillary 

 net-work, but not the glomeruli, are filled ; and for the study of the vasa 

 ejf'erentia from the arteries, preparations not completely filled with injection 

 are to be used. The course of the urinary tubules is to be studied on fine 

 sections of kidneys, hardened first in alcohol, then by boiling in diluted 

 nitric acid and drying ( Wittich), on kidneys hardened in chromic acid, and 

 afterwards rendered clear by acetic acid : or the tubules may be studied on 

 sections made by the double knife on fresh or injected kidneys ; and on these 

 sections we may recognise the important fact of the division of Bellinian 

 tubules. Still it is always useful to inject the uriniferous tubes, and for this 

 object the kidney of the horse is better adapted than that of any other mam- 

 malian. Such an injection may be produced accidentally by extravasation into 

 the Malpighian capsules in the process of injecting the arteries ; but then, 

 however, seldom more than the tortuous tubules are filled. It is better 

 to inject them from the ureter with the aid of the air-pump (Huschke, Isis, 

 1826); or whilst the pelvis of the kidney is kept- constantly filled, the size 

 may be forced into the straight tubules, and beyond these into the tubules 

 of the cortex, by kneading the calyces with the hand (C'ayla). The individual 

 tubules may also be injected directly from the papilla by means of very fine 

 canulas. 



Literature. — Malpighi, de rcnibus, in Exerc. de vise, struct. Al. Schum- 

 lansky, Diss, de struct, rcnum. c. tab. Argentor, 17S2, 4. W. Bowman, On the 

 Structure and Use of the Malpighian Bodies of the Kidney, in Phil. Trans., 

 1842, I., p. 57. C. Ludwig, Beitr'dge zur Lehrevo?n Mechanismus der Harttse- 

 crction, Marburg, 1843 ; and Art. Mere in Wagner's Handm. II., p. 628. J. 

 Gerlach, in Mull. Archie, 1845 au ^ 1848. Kolliker, in MiiLL. Archiv., 1845. 

 Remak, in Fror. JV.Not., No. 768, 1845, p. 308. F. Bidder, in MiiLL. Archiv., 

 1845 ; and TJntersuchungen ubcr die Gesehlechts- and Harnmcrlizcuge der 

 Amphibien, Dorpat, 1846. J. Hyrtl, in Zeitschrift d. Wien Aertze, 1846. 

 C. v. Patrdban, Beitr'dge zur Anatomie der mcnschlichen JYierc, in Prag. 

 Viertelj., 1847, III. G. Johnson, Art. Pen, in Cycl.of Anat., May, 1848. V. 

 Carus, in Zeitschr.f. wiss. Zool., II., p. 61 ; v. Wittich, in Arch.f. path. Anat., 

 III., i., 1849; v. Hessling, in Fror. Not., 1849, P- 26 4> an d Histologischc 

 Beitr'dge zur Lehre von der Ham-secretion, Jena, 1851. Frerichs, Die 



