1888.] MICROSCOPICAL JOURNAL. 19Y 



faces of the cells. 6. Shape of the cells as a whole. 7. Shape of the surface 

 of the growing- mass, whether flattish or consisting of numerous processes. 

 8. Relation of blood vessels to the growing mass. 9. Degree of compres- 

 sibility of individual cells. 10. Degree of cohesion between the cells. 



An epithelium cell is most hardy, for it lives separated from blood by base- 

 ment membrane, and often by other cells. It often receives nourishment at 

 one end only of cylinder cells. Such a cell, then, if it penetrated the base- 

 ment membrane, would seem able to outstrip competitors of other tissue. 

 The epithelium cell is also a rapid grower. Its ordinary mode of death is 

 by abrasion, while the ordinary mode of death of mesoblastic tissues is by 

 fatty degeneration and resorption. In the protected situation, and well nour- 

 ished, we may easily suppose the epithelium cell to be endowed with great 

 vitality. The epithelium is very incompressible and of angular contour. 

 Hence accumulations would force them through basement membrane, and the 

 mass is also angular, which would force it out among the tissues. In com- 

 petition with them they would come out the worse. The cells also have a 

 secretion of thfeir own which does not escape, and the}^ are not very closely 

 attached to each other. Thus single ones can become detached and force 

 themselves into new situations. For these reasons encapsulation is very un- 

 likely in epithelial growths. In encapsulated growths, as fatty tumors, the 

 normal parts with their blood vessels are merely thrust aside, but where the 

 basement membrane is broken thi'ough the normal tissues are invaded. 

 Fatty tumors contain no blood vessels ; epithelioma are vascular. This, 

 then, answers the question why epithelial proliferations are malignant, while 

 others, e. _^. .fat or inorganic muscle, are not so. 



A second question arises, how does epithelium get below the basement 

 membrane ? There are two modes of answer : — i , great pressure from growth ; 

 2, weakening of basement membrane. Both may co-operate. The former 

 may result from various causes: — i. A blow, e.^., on the breast without 

 lesion of skin, but a deeper injury. 2. Gland with age may have lumen 

 blocked. 3. Result of mechanical pressure, e. ^., a pipe on the lips. 4. 

 Excited growth in the deepest layers may cause to burst the epithelium as 

 the easiest outlet. 



How is the proliferation caused ? Perhaps by removal of the force of 

 formative restraint which keeps a balance among tissues, or by the addition 

 of an unknown force. Old age or carnivorous diet seem to be disposing 

 causes. 



QUERIES. 



I. What is the most convenient way to catalogue and arrange histological and 

 pathological specimens ; about i ,000 ? — V. A. L. 



A. — From our own experience we should answer the question as follows : — In work- 

 ing out a study in molluscan embryology, which required the cutting of 75 embryos 

 and of 200 sections of each embryo, the problem of how to find anything in particular 

 soon became a very pressing one. We numbered the series of sections with a num- 

 ber for each embryo, and the section in each series from its particular place in that 

 series. The whole set of sections was kept together and designated by the name of 

 the animal under investigation. We could then readily refer most minutely to any 

 section in the entire collection. Fasc, 5, 23, for instance, meaning a certain small 

 spot, by examination of which we should see a certain peculiar cell nucleus, or some 

 other minutiae, which a tiresome search might not otherwise discover. To find these 

 places a catalogue was then made by subject, with references as above. We consider 

 the best mode of arrangement to be, first, by organ, the sections of any one organ 

 being numbered, and if several sections of the same piece are cut these receive addi- 

 tional numbers ; thus, liver, 6, 5, would be the designation of a particular section in a 

 series. 



