70 The Normal Histology of the Human Hemolymph Glands 



ence of a blood-sinus, however small, is sufficient warrant for the 

 classification of a gland as a hemolymph gland. 



The microscopical study of the lymphoid nodes containing blood- 

 sinuses reveals a most striking variety of structure in so far as the 

 relative size, number and arrangement of the blood-sinuses, lymphoid 

 tissue, etc., are concerned. It is possible, however, to divide the dif- 

 ferent forms into two distinct types, to which I have given the names 

 splenolymph and marrowlymph gland as indicating their structure and 

 probable functions. Between these two there is every possible transi- 

 tion-form, just as there is also between the spleen, hemolymph glands 

 and ordinary lymphatic glands. It is not by any means intended to 

 replace the designation, hemolymph gland, by these names, as the latter 

 should still be used as a collective term. 



Splenolymph Glands. 



The great majority of hemolymph glands correspond to this type. 

 They are found chiefly along the abdominal aorta, vena cava, adrenal 

 and renal vessels, in the neighborhood of the solar plexus, cervical re- 

 gion, occasionally in the omentum, mesentery, epiploica, mediastinal 

 and thoracic prevertebral regions. These glands are usually round, 

 but also frequently almond-shaped, varying in size from a pin-point to 

 a large cherry. As a rule they possess a distinct hilum into which 

 numerous vessels of large size enter. These are also found penetrating 

 the capsule at many points. Very often the gland appears to be sur- 

 rounded by a plexus of vessels, sometimes arterial, at other times 

 venous. Their gross appearances correspond with those given above 

 for hemolymph glands in general. Their resemblance to the spleen is 

 sometimes so great that they may be mistaken for accessory spleens, 

 aild undoubtedly many of the so-called accessory spleens belong to this 

 type of hemolymph gland. This fact was dimly recognized by Haberer 

 in his recent article "Lien Succenturiatus und Lien Accessorius" 

 (Arch. f. Anat. u. Phys., March, 1901). Apparently unaware of the 

 existence of hemolymph glands this observer concluded that many 

 glands regarded as accessory spleens were in reality peculiar types of 

 lymph glands representing intermediate forms between spleen and 

 lymph glands. • 



Capsule. — The splenolymph glands possess a capsule of connective 

 tissue which may be very thick in proportion to the size of the organ 

 or very thin and delicate. It contains a varying amount of unstriped 

 muscle, and very little yellow elastic tissue. Adipose tissue surrounds 

 the capsule. The latter is frequently pierced by many obliquely-pene- 



