134 PHYSIOLOGY AT THE FARM. 



even sometimes muscular fibres of the plain variety. The outer 

 coat is perfect, unless where it gives passage to the absorbents 

 themselves and the larger blood-vessels. This part of the gland, 

 presenting a fissure or depression, is called the hilum. The 

 gland itself is composed of an outer cortical part, and an inner 

 medullary part. The cortical part surrounds the medullary 

 part, except at the hilum, and in large glands attains a con- 

 siderable thickness. From the outer areolar coat numerous thin 

 partitions run inwards, so as to form many loculaments of a 

 polygonal figure. These loculaments are filled with a whitish 

 pulpy matter made up of cells and nuclei, identical in character 

 with the corpuscles of the lymph and chyle. When this sub- 

 stance is washed out, each loculament is seen to be crossed in 

 all directions by numerous fine columns or trabeculse, subdivid- 

 ing its interior into a great many smaller intercommunicating 

 cavities, and giving origin to a spongy structure, in the meshes 

 of which the pulpy matter is lodged. Fine capillary blood- 

 vessels are supported within by the larger trabeculae. 



This spongy structure belongs only to the cortical part of 

 the gland. The medullary part in the centre of the gland 

 consists of a plexus of absorbent vessels which directly com- 

 municate with the absorbent trunks, which issue from the 

 gland at the hilum. It should be borne in mind that the lac- 

 teals which enter a conglobate gland are termed the afferent 

 vessels (vasa afferentia), and those which issue efferent vessels 

 (vasa efferentici). It appears, then, that the afferent vessels enter 

 the gland at various points of its surface, and open by fine 

 branches into the meshes of the spongy structure of the cor- 

 tical part ; and that other fine vessels take their rise from the 

 cavities of that spongy structure, and pass to the central plexus 

 in the medullary part, whence the efferent vessels originate, and 

 these pass out solely by the hilum by which the blood-vessels 

 enter and issue. 



