LEPIDIC AND HYLIC TISSUES 313 



appears to me most important. While some pathologists, like 

 Buxton x and 0. Israel, 2 have already noticed this distinction, 

 I do not know that histologists and embryologists have called 

 adequate attention to it. Though I am strongly against the 

 coinage of new scientific terms, there are occasions when this is 

 absolutely necessary, and this appears to be pre-eminently one 

 of these occasions. Thus, I would term the lining membrane 

 tissues lepidic, from \e7rt?, XeirlSo^, a rind, skin, or membrane ; 

 and what I have termed the pulp tissue hylic, from v\r], crude 

 or undifferentiated material or matter. 3 We can go further 

 and subdivide each of these main groups according as to whether 

 the tissues are of epiblastic, hypoblastic, mesothelial, mesenchy- 

 matous, or endothelial origin. On this basis we obtain the 

 following classification of normal tissues : 



I. Lepidic or Lining Membrane Tissues 



in which the blood-vessels do not penetrate the groups of specific 

 cells, and in which there is an absence of definite stroma between 

 the individual cells, although such stroma, of mesenchymatous 

 origin, may be present between the groups of cells. 



1. Epiblastic. 



Epidermis. Epidermal appendages — hairs, nails, enamel of 

 teeth, etc. Epidermal glands. Epithelium of the mouth, 

 salivary glands. Epithelium and glands of nasal tract and 

 associated spaces. Epidermal portion of hypophysis cerebri. 

 Lens of eye. Epithelium of membranous labyrinth of ear, 

 anus, male urethra (except prostatic portion). 



2. Hypoblastic. 



Epithelium of digestive tract and glands connected with it. 

 Specific cells of liver, pancreas, tonsils, thymus, thyroid. 

 Epithelium of trachea, lungs, bladder, female urethra, male 

 urethra (prostatic portion). 



3. Mesothelial. 



Lining cells of pleurae, pericardium, peritoneum. Specific cells 

 of suprarenals, kidneys, testes, ovaries (Graafian follicles). 

 Epithelium and glands of Fallopian tubes, uterus, vagina, 

 vasa deferentia, vesiculae seminales, etc. 



1 Buxton, Journ. Cutan. and Gen.-Urin. Dis. xviii., 1900, 74. 



2 Israel, Berliner klin. Woch. xxxvii., 1900, 609, 644, 667. 



3 I would here acknowledge my indebtedness to Principal [now Sir William] 

 Peterson of McGill University for aid in the selections of these terms. 



