244 



KEN. 



on the other with the veins, and invested by 

 a cellular tissue in a manner which he does 

 not very clearly explain. He believes that 

 there is a close connexion between the Mal- 

 pighian bodies and the tubes, as manifested 

 by the fact, that the tubes may be filled by a 

 forcible injection of the Malpighian bodies 

 through the arteries : further confirmation of 

 this fact being afforded by the occasional pas- 

 sage of blood and other materials through the 

 same channels, and the tubes being found 

 filled with blood after death. With respect 

 to the last observation, which he quotes from 

 Bertin, he appears to have some doubt, and 

 suggests that the vessels containing the blood 

 may have been blood-vessels, and not urinife- 

 rous tubes. 



Since the time of Schumlansky, whose 

 work above quoted was published in the year 

 1788, scarcely any addition was made to our 

 knowledge of the structure of the Malpighian 

 bodies until the publication of Mr. Bowman's 

 paper*, already so often referred to. In some 

 respects, indeed, the description given of the 

 Malpighian bodies by the best anatomists im- 

 mediately before the appearance of Mr. Bow- 

 man's paper, is less accurate than that of 

 Schumlansky, and some of his predecessors. 

 Thus, Miiller-f denied, in the most positive man- 

 ner, the existence of any connexion between 

 the Malpighian bodies and the tubes, and the 

 possibility of injecting the latter from the 

 former. Professor Miiller has since J acknow- 

 ledged and confirmed the accuracy of Mr. 

 Bowman's observations, which I shall now 

 proceed to detail as much as possible in his 

 own words, because it would be impossible to 

 depart much from the language of his paper 

 without incurring a risk of losing something 

 of the clearness which characterises the 

 original. 



The Malpighian bodies consist of a rounded 

 mass of minute blood-vessels, invested by a 

 cyst or capsule. The capsule was first par- 

 ticularly described by Miiller, who believed it 

 to be closed oh all sides except at one point, 

 where it is perforated by the blood-vessels. 

 He accurately described the arterial branch as 

 passing into the cavity of the capsule, where 

 it gives off tortuous branches, which form 

 arches, and then return to the point at which 

 the artery enters, so that the tuft of vessels is 

 free in the cavity of its investing capsule, 

 being connected with the latter only at one 

 point. Mr. Bowman, observing that the cap- 

 sule of the Malpighian bodies had an appear- 

 ance precisely similar to that of the basement 

 membrane of the tubes, and seeing these 

 similar tissues in such close proximity, was 

 led to suspect that the capsule was in fact the 

 basement membrane of the tubes expanded 

 over the vessels, and after some time he suc- 

 ceeded in obtaining an unequivocal view of 



* On the Structure and Use of the Malpighian 

 Bodies of the Kidney. Philos. Trans, part i. 1842. 



f J. Miiller, de Glandularum Secernentium 

 Structura Penitiori. Lips. 1830. 



J Untersuchungen tiber die Eingeweide der Fische. 

 J. Mttller, Berlin, 1845. 



their continuity. This important result was 

 arrived at after the use of the double injection. 

 After the injection of some kidneys through 

 the artery by this method, it was found that 

 the injected material had in many instances 

 burst through the tuft of Malpighian vessels, 

 and being extravasated into the capsule, had 

 passed off along the tube. (Figs. 153.3. 156, 157.) 

 Mr. Bowman afterwards made numerous injec- 

 tions of the human kidney, and of that of many 

 of the lower animals, and in all, without excep- 

 tion, he met with the same disposition. He 

 also examined thin slices of the recent organ 

 with high powers of the microscope, and 

 in this manner fully corroborated the evi- 

 dence furnished by injections. This mode of 

 examination likewise led Mr. Bowman to the 

 very interesting discovery of ciliary motion 

 within the orifice of the tube and the con- 

 tiguous portion of the Malpighian capsule. 

 According to the observations of Mr. Bow- 

 man, the circulation through the kidney may 

 be stated to be as follows : " All the blood 

 of the renal artery (with the exception of a 

 small quantity distributed to the capsule, sur- 

 rounding fat, and the coats of the larger 

 vessels,) enters the capillary tufts of the Mal- 

 pighian bodies; thence- it passes into the 

 capillary plexus surrounding the uriniferous 

 tubes, and it finally leaves the organ through 

 the branches of the renal vein." (Fig. 152.) 



Fig. 152. 



tn. 



Plan of the renal circulation in Mammalia. 

 (After Bowman.} 



The relative proportions and the character of the 

 several parts are accurately copied from preparations 

 of the human kidney. The artery, a, is seen giving 

 a terminal twig, f, to a Malpighian tuft, m, from 

 which emerges the efferent (or portal) vessel, d. 

 Other efferent vessels are seen, e, e, e. All these en- 

 ter the plexus of capillaries, p, surrounding the 

 uriniferous tube, t. From this plexus the emulgent 

 vein, <;, springs. Supposed to be magnified about 

 forty diameters. 



Following it in this course, I shall now give 

 Mr. Bowman's description of the vascular 

 apparatus, and the nature of its connexion 

 with the tubes. I shall also refer to some 

 observations which have been made since the 

 publication of Mr. Bowman's paper, premising 

 that Mr. Bowman's description is so singu- 

 larly accurate that it scarcely requires or 

 admits of any, even the slightest, addition or 

 modification, with reference to those par- 

 ticulars which it embraces. 



