CENTRES OF NUTRITION. 391 



There is one form in which nutritive centres are arranged, 

 both in healthy and morbid parts, which is frequently alluded 

 to in the following chapters, and which may be named a 

 germinal membrane.* In a germinal membrane, the nutritive 

 or germinal centres are arranged at equal or variable distances, 

 and in certain directions, in the substance of a fine trans- 

 parent membrane. A germinal membrane is occasionally 

 found to break up into portions of equal size, each of which 

 contains one of the germinal centres. From this it is per- 

 ceived that a germinal membrane consists of cells, with their 

 cavities flattened, so that their walls form the membrane by 

 cohering at their edges, and their nuclei remain in its sub- 

 stance as the germinal centres. 



Germinal membranes are only met with on the free 



centre, and more especially of the appearance of new centres within the ori- 

 ginal sphere, we are indebted to the researches of Dr. Martin Barry. "What- 

 ever may be said in opposition to Dr. Barry's views regarding the functions of 

 the blood-globules, and the structure of muscular fibre, he is yet entitled, 

 above all physiologists of the present day, to the merit of having kept steadily 

 before him in his researches the principle of the central origin of all organic 

 form. 



* The membranous tubes of glands on which the epithelium is situated 

 were described by Henle, Miiller's Archiv, 1839. Mr. Bowman (Phil. Trans. 

 1842) " On the Structure and Use of the Malpighian Bodies of the Kidney," etc., 

 has applied to the membrane of these tubes the very appropriate name of 

 Basement Membrane. This membrane I consider to be a primary or germinal 

 membrane. The term, basement membrane, is good as involving no 

 hypothesis ; it is therefore a most appropriate descriptive term. I have always 

 considered the basement membrane, or elementary membrane of glands, as a 

 form of the primary cells of glands, and the source of the secondary or 

 secreting cells, and have therefore been in the habit of naming it primary, or 

 germinal membrane. Mr. Bowman considers it to be simple, or homogeneous. 

 This is true as far as it contains no bloodvessels, and as regards its external 

 or attached layer ; but as in its original condition it consists of cells, and when 

 perfect contains nuclei at equal or variable distances, I do not consider it as 

 simply molecular. These nuclei, or germinal spots, may be certain of the 

 epithelial cells, which become mother-cells, between the two layers of the 

 membrane ; or cells belonging to the order of the nuclear fibres of Valentin 

 and Henle. 



