DUCTLESS GLANDS. 337 



the notch formed by the branching of a vessel, and in others 

 attached to an extremity of an arterial twig, the vessel then 

 breaking up into a plexus to surround the corpuscle. Ac- 

 cording to Sappey, the corpuscles are attached to arteries 

 measuring from -g^ to -^ of an inch or less in diameter. 1 

 When the artery is enclosed in its fibrous sheath, the corpus- 

 cles are applied to the sheath, but in the smallest arteries 

 they are attached to the walls of the vessel. The attach- 

 ment of the Malpighian bodies to the vessels is very firm, 

 and they cannot be separated without laceration of the 

 membrane. 



Spleen-pulp. "With, regard to the constitution of the 

 spleen-pulp, there is considerable diversity of opinion. 

 While anatomists and physiologists are pretty generally 

 agreed concerning the structure and relations of the Mal- 

 pighian bodies, some minutely describe cells in the pulp, the 

 existence of which is denied by others of equal authority. 

 The pulp, however, contains the essential elements of the 

 spleen, and an accurate knowledge of all the structures con- 

 tained in it could hardly fail to throw some light on its func- 

 tion ; but there is so little that is definitely known of either 

 the anatomy or the physiology of the spleen, that we shall 

 refrain from discussing the views of different authors, refer- 

 ring the reader for full information upon these points to the 

 elaborate works upon general anatomy. 



The pulp is a dark, reddish, semifluid substance, its color 

 varying in intensity in different specimens. It is so soft that 

 it may be washed by a stream of water from -a thin section, 

 and it readily decomposes, becoming then nearly fluid. It is 

 contained in the cavities bounded by the fibrous trabeculae, 

 and itself contains numerous microscopic bands of fibres 

 arranged in the same way. It surrounds the Malpighian 

 bodies, contains the terminal branches of the blood-vessels, 

 and probably the nerves and lymphatics. Upon microscopi- 



1 Op. tit., p. 328. 

 22 



