The Vascular Glands. 77 



the blood in a horse's body, and to require two men to 

 lift it out of the abdomen after death. 



Roy has shown that the spleen is possessed of rhythmical 

 movements, expanding and contracting at regular intervals 

 through the medium of the muscular fibres of the capsule, 

 and not by means of the blood pressure, of which the 

 circulation in the spleen is found to be independent. The 

 muscular movement is under the control of automatic 

 ganglia situated in the organ itself. Tizzoni asserts that 

 new splenic structures are formed in the omentum of the 

 horse and dog after destruction of the spleen (Landois). It 

 is certain that when the spleen is destroyed that the 

 lymphatic glands and red marrow of bones become, as a com- 

 pensatory effect, more active in forming red blood cells. 



The Thymus is especially active during intra-uterine 

 existence, and for a short time after birth. It forms blood 

 corpuscles, in this way assisting the other tissues engaged 

 in this operation, at a time when the greatest activity is 

 required from them — viz., during early life. The thymus 

 disappears towards puberty ; in the horse and ox at two years 

 old. In hybernating animals it acts as a storehouse for fat. 

 The Thyroid is connected with the production of mucin in 

 the body, for removal of this gland gives rise to myxoudema, 

 or mucinoid degeneration of the tissues ; the composition 

 of the blood is also affected by its removal, for there is a 

 reduction in the number of red cells and an increase in the 

 white. Removal of the thyroid leads to a fatal cachexia. 

 Professor Horsley, whose name is intimately connected with 

 what is known of the functions of this body, has shown 

 that both ruminants and horses suffer from fatal cachexia 

 after removal of the thyroid. The function of this gland 

 is quite obscure; it is considerably more active in intra- 

 than in extra- uterine life. 



The Anterior Renal Capsules have been supposed to be 

 connected with the removal of the worn-out pigment from 

 the body. Their function is involved in mystery. 



The function of the Pineal and Pituitary bodies, though 

 classed as blood glands, is absolutely unknown. The pineal 

 is considered to be the remnant of an ancestral eye. 



