138 



ANATOMY AND PHYSIOLOGY OP THE HORSE. 



intestines also extract nutriment from their contents, 

 ■which is proved by the fact that nutritious matter in- 

 jected into tliem has been knoMii to support life for a 

 certain time. 



SPLEEN. 

 Q. "What is the function of the spleen? — A. It 

 serves as a Icind of diverticulum, to relieve the vessels 

 of the digestive vescera when they are compressed by 

 undue accummulation of the contents of their cavities, 

 or ■when they are congested by obstruction to the flow 

 of blood, tlu'ough the liver or heart. It may also be 

 considered as a lymphatic gland, for, in some instances 

 in wliich animals have been allowed to sm-nve longest 

 after removal of the spleen, the Ij-mphatic glands of 

 the ^icinity have been found greatly enlarged and clus- 

 tered together, so as nearly to equal the origmal spleen 

 in volume ; hence, in such case we infer that its func- 

 tion must be similar to that of the enlai-ged IjTuphatic 

 glands. 



LIVER. 



Q. What comprises the principal bulk of the liver ? 

 — A. It is made up of a vast number of minute lobules 

 of irregular form, but about the average size of a mil- 

 let seed ; and each of them contains the elements of 

 which the entii-e organ is composed, ^■^z., a plexus of 

 biliaiy ducts connected M-ith their main trmiks, and a 

 mass of biliary cells ; each of -which are connected in 

 like manner with the three blood-vessels ■which imite 

 to the circulation of this organ. 



Q. What are the vessels of the Hver? — A. The 

 hepatic artery, vena portae, and hepatic veins, to ■which 

 may be added the excretory ducts and absorbents. 



Q. Of what use is the hepatic artery .f — A. It is the 

 nutrient arteiy of the liver. 



Q. Of what use is the vena portae ? — A. It acts both 

 as a vein and arterj' : as a vein, it receives the blood 

 from most of abdominal -riscera ; as an arterj', it rami- 

 fies through the Uver for the secretion of bile. 



Q. What is the use of the hepatic veins ?-—^. They 

 retm-n blood to the vena cava. 



Q. AMiat is the function of the liver ? — A. It is an 

 organ of excretion, designed to remove from the ckcu- 

 lating fluid that portion of the products of disintegra- 

 tion, of which the principal component of the lu'inary 

 is the largest. 



Q. Into what substance is the greater part of the 

 excrcmentitious matter converted ? — A. Biline. 



KIDNEYS. 



Q. T^^lat is the cmbryotic condition of the kidneys ? 

 A. The kidneys are preceded in the embryo by a sub- 

 stance first noticed by Wolff", and called after him the 

 Wolffian bodies," or false Iddneys, which originally ex- 

 tend along the spme from the heart to the end of the 

 intestines; but they afterwards become shorter, and 

 after a time diminish by absorjition, and wholly dis- 

 ajipear. 



Q. What is the function of the kidneys ? — A. Their 

 principal function is to separate from the blood certain 

 matters which would be injurious to it if retained. 



Q. What does the secretory surface of the kidneys 

 consist of? — A. It is composed of epithelial cells 

 wliich line the tubidi m'inifera, which draw the peculiar 

 elements of the m'inary excretion fr-om the vascular 

 plexus which surrounds the exterior of the tubes, car- 

 rjing oS" the same to their terminations in the ureter. 



Q. AVhat other arrangement is provided "nithin the 

 kidneys for the elimination of the superfluous fluid of 

 the blood? — A. A process of transudation takes place 

 by the function of malpighian bodies, whose thin-walled 

 capillaries allow the transudation of water to take 

 place, under a certain pressm-e, into the tubuli urinifera. 



SUPRA-EENAL CAPSULES. 



Q. What is the function of the supra-renal cap- 

 sules ? — A. Then- function has hitherto been involved 

 in obscurity, and was supposed to be identical ■with 

 other glands destitute of ducts or outlets ; but, lately, 

 M. Broivn Seguard has demonstrated that they play 

 a very important part in the nervous system of the 

 horse. 



VASA DEFEEENTM.. 



Q. What is the function of the vas deferens ? — A. 

 It is the excretory duct of the testicle, and conveys the 

 semen to the vesiculae seminales. 



The author, instead of introducing examinations on 

 tlie reproductive organs, has thought it best to substi- 

 tute the opinions of that eminent phyisologist, Dr. 

 Cai'penter ; and therefore the reader's attention is now 

 directed to " Physiological considerations on the re- 

 production of organized beings.^' 



