140 HOW TO WORK 



points may be shown in one preparation. Beautiful specimens of 

 this kind may be prepared by injecting one vessel with the acid 

 carmine and the other with Prussian blue fluid. See pages 95, 97. 



Thin sections may be cut with Valentin's knife or with the 

 double-edged scalpel ; and it is desirable to take several thin sections 

 from the surface of the organ. The sections may be preserved in 

 fluid or dried and mounted in Canada balsam ; I much prefer 

 glycerine as the preservative medium. 



Artery. The surface of the organ is supplied by an extensive 

 arterial network, and the portal canals also contain a similar net- 

 work. The coats of the ducts are largely supplied with arterial 

 blood, and the finer ducts are in close relation with numerous small 

 branches of the artery. The precise mode in which the blood is 

 poured into the veins has been a subject of great dispute, but I have 

 many preparations which show that the blood is poured into the 

 portal capillaries near the circumference of the lobule as Kiernan long 

 ago inferred, and not into those near the centre, Phil. Trans., 1833. 



240. of injecting the~Ducts of the Liver. The method of inject- 

 ing the ducts of the liver has been already described in page 101. 



Since the publication of my paper in the Phil. Trans, for 1855, 

 and memoir upon the anatomy of the liver, in which this mode of 

 investigation was described, 1856, several views concerning the 

 arrangement of the ducts absolutely incompatible with my own have 

 been advanced by continental anatomists. The plans which I 

 followed have been repeated several times, and have in every instance 

 confirmed the results which I previously arrived at. I have quite 

 recently (1867) re-studied this subject and have succeeded in making 

 some preparations which are quite conclusive as to the continuity 

 of the ducts with a cell containing network in the lobule.* 



241. Kidney. The Anatomy of Glandular Organs more easily 



* It is curious to observe how positively some reiterate the assertion that the mam- 

 malian liver does not possess a tubular structure Quite recently Ewald Hering, of 

 Vienna, after admitting that the vertebrate liver in general is to be regarded as a 

 "reticularly arranged tubular gland," goes on to say that "all the oft-repeated 

 accounts of a tubular structure of the mammalian liver, I must point out as errone- 

 ous (!). For instance, Beale's familiar representation, which is intended to demon- 

 strate the tubular structure of the pig's liver, shows me plainly that a completely 

 ruined (!) preparation was the foundation of it. The injection mass is extravasated 

 out of the gall ducts, the liver cells are distorted from their natural position, and to 

 such an extent destroyed. Beale has also investigated the liver of cold-blooded 

 vertebrata, and this may have misled the distinguished microscopist in supposing (!) 

 analogous circumstances for the mammalia." I can assure this observer that my 

 specimen was not ruined, that I saw what I affirmed, and have never advanced as 

 demonstrations what are but suppositions. Further observations I venture to think 

 will convince Hering that the mistakes and suppositions are not on my side. 



