2 Th. Lewis, 



I. Introductory. 



During the past twenty years numerous contributions liave ap- 

 peared at irregular intervals upon the subject of luTemolymph and 

 lymphatic glands. The function, or functions of these organs seem 

 however, until comparatively recently, to have been to a great extent 

 misunderstood, and are even yet not duly appreciated. 



The investigation recorded in the following pages, was commenced 

 in the hope of giving a connected review of the numerous articles 

 on this subject, and of clearing away some of the difficulties and dis- 

 crepancies encountered by previous workers. 



As the rat furnishes a ready and convenient source of fresh 

 material, I have found it advantageous to make a careful examination 

 of the glands in this animal the foundation of my work, extending 

 it to similar and related organs in other animals. In this extension, 

 which has necessarily been wide, the chief British mammals have 

 been dissected; the general distribution of the structures has been 

 recorded, and histological observations have in all cases been made. 

 By the term "related organs'" I signify such structures as the spleen, 

 accessory spleens, ordinary lymphatic glands, and mau}^ intermediate 

 forms. In regard to the nomenclature of these intermediate forms 

 considerable confusion has arisen; in some cases they have been clas- 

 sed in the common category, ^'hœmolymjjh glands". In other cases 

 this term has been restricted to such typical blood-red glands as are 

 found in the horse, ox, or sheep. Yet again they have been des- 

 ignated ^'hcemal glands", or "hceìiial lymphatic glands". So great 

 has been this confusion that it is desirable to carefully define the 

 different structures, and to make an attempt to fix a terminology 

 which shall distinguish the various forms of glands. 



As will be found from a perusal of the following pages, the 

 glands may be divided into three classes, which are named, under the 

 terminology proposed, according to the character of the fluid spaces 

 found within them. In the first instance we may retain the term 

 "hcemolymph", which was originally used by Lankester as a general 

 term to include the red and white corpuscles of the blood; it seems 



