256 Genetic Interpretations in the Domain of Anatomy 



to the position of the thymus, I feel quite uncertain and hardly dare to 

 say whether it should be placed among the epithelioid glands or among 

 the cell-producing glands. Similarly, how to place the interstitial cells 

 of the genital glands in our system is not yet quite clear to me. The 

 third division is that of the cytogenic glands, and of these we may 

 readily distinguish three important types : the first, those in which lymph 

 cells arise ; second, those which produce red blood corpuscles ; and third, 

 those which yield the genital elements. The glands of the first type may 

 be called lymphseal structures. " Lymphajal " is a new term derived 

 from " Lymphseum," itself a new technical expression, which I have used 

 for severr.l years in my lectures on histology and have found advantageous. 

 A lymphgeum may be defined as follows : it is a site for the multiplication 

 of leucocytes and is a more or less definitely circumscribed area consisting 

 of cellular reticulum, the meshes of which are charged with leucocytes 

 and are in direct communication Avith lymph-vessels, or more rarely Avith 

 blood-vcf^sels. The following offer examples of lymphasa: solitary fol- 

 licles, tonsils, thymus, lymph glands, hsemolymph glands and spleen. 

 As stated above, whether the thymus should belong in the first or third 

 division, I cannot say. Of the second type in this division, the bone 

 marrow is the most important example. Of the third type, that of the 

 genital glands, we have of course to distinguish two forms, the ovary and 

 the testis. 



With these explanations, I hope the accompanying table will be clear 

 and I trust that the proposed new classification of glands will seem to you 

 both more scientific and more available than the classification now pre- 

 valent, which I should like to see displaced. 



TABLE II. CLASSIFICATION OF GLANDS.= 



Class A. Unicellular. 



Class B. True Glands, always developed with ducts. 



Division 1. Simple Olands, {unifollicular or single glands). 



a. Ectodermal. 



1. Sweat glands. 



2. Sebaceous glands. 



3. Buccal glands. 



b. Entodermal. 



1. CEsophageal. 



2. Gastric. 



3. Intestinal. 



c. Mesothelial. 



1. Uterine. 



