1877.] 



Bodies of the Horse and Bog. 



503 



structure of the cortical zone is not of a kind to suggest or to bear out 

 the above comparison. But, according to Henle, the peculiar structures 

 of the horse and dog are occasionally found in other mammals. An 

 occasional reappearance is what might be looked for in an obsolete 

 structure. But, exact similarity apart, there is in the suprarenals of all 

 mammals a zona glomerulosa, which corresponds to the cortical zone 

 above described ; and the zona glomerulosa, being subject only to laws of 

 heredity, and not to laws of function, may be considered in most 

 mammals to have lost those distinctive features which survive, for un- 

 explained reasons, in the dog and horse. Again, as regards the parallel 

 structures in the ovary, they are seen clearly in the bitch, are indistinctly 

 seen in the cat, and are not to be distinguished in the mare. But those 

 differences are not fatal to the generalization, and explanations are 

 offered of them. 



In the second section of the paper the author describes the resem- 

 blance of the general intracortical mass of the suprarenal to another 

 class of ovarian structures, viz. corpora lutea. The corpora lutea here 

 spoken of are large cellular masses of very definite and stable struc- 

 ture, occurring at various points in the ovary, and in some cases of so 

 great extent as to transform the ovary into an organ of altogether new 

 appearance. Instances are referred to of ovaries from the mare and 

 bitch in which corpora lutea seemed to have greater persistence than is 

 usually attributed to them, and it is held that the prevalent theory of 

 the circumstances of their formation and decay is not comprehensive 

 enough. 



Taking, however, the corpora lutea as they are found, and directing 

 attention to their minute structure, they have the following points of 

 resemblance to the intracortical mass of the suprarenal. Both struc- 

 tures are cellular throughout, and the individual cells are the same. The 

 cells are epithelial-like and polyhedric, with a central nucleus and a wide 

 zone of cell-substance. The cell-substance in both cases is so coarsely 

 granular as often to resemble the vitellus of the mammalian ovum, and 

 in both cases the granular protoplasm is sometimes replaced or occu- 

 pied by a vacuole. The one point of difference is that the cells of the 

 corpus luteum are half as large again as those of the suprarenal paren- 

 chyma. The second point is that the cells in both cases are set in a fine 

 meshwork of fibres connected with the walls of the capillaries. Thirdly, 

 there is, in both, the same radial arrangement of blood-vessels (capil- 

 laries) from centre to circumference. Fourthly, the central vein or 

 system of venous lacunae of the suprarenal has its counterpart in the 

 corpus luteum. Lastly, there are points of resemblance relating to the 

 pigmentation of the respective structures. 



Although it is not essential to the justice of the comparison that the 

 obsolete Graafian follicles should have the same position round the cir- 

 cumference of corpora lutea which the cortical suprarenal follicles have 



2n2 



