74 HISTOLOtiY OF THK l'< >1S( ).\-(,' LANDS OF BUFO ACl'A. 



the mechanism of its synthesis, and to determine the distribution of chromaffin cells in 

 other tissues throughout the animal's body and their relation to the production and storage 

 of the epinephrin content of the crude venom. 



The results, while throwing some light on certain of these questions, leave others still 

 in darkness, and a great deal more must be done by the embryologist and biochemist before 

 the mechanism of venom secretion and elaboration in these interesting glands can be at all 

 fully understood and the discussion of their physiology regarded as closed. 



MATERIAL AND METHODS. 



.Since the purpose of this communication was only to describe the various depots of 

 chromaffin tissue and material, almost all the tissue studied was fixed in a modified Orth's 

 solution of the following composition: 



3.5 per cent aqueous solution of potassium bichromate. . 90 c.c. 



40 per cent formalin 10 c.c. 



A large number of stains were used alone and in combination : hematoxylin and eosin, 

 iron hematoxylin, Weigert's elastic tissue stain, Mallory's stain for connective tissue, and 

 hematoxylin counterstained with Van CJieson's mixture. The sections of the poison-glands, 

 adrenal, and sympathetic ganglia were made with the ordinary celloidin technique. Tissue 

 prepared for the study of fat was fixed in 5 per cent and 10 per cent solutions of formalin, 

 and cut in thin sections with a freezing microtome after careful washing in distilled water. 

 These frozen sections stained with hematoxylin and counterstained with alkaline Sudan III 

 were found very useful (fig. 10) in studying the relations of the adrenal cortex to the medulla 

 of that organ. 



Eviscerated animals were stuffed with cotton soaked in formol bichromate, and after 

 being carefully wrapped in linen were packed in an ice-chest for 24 hours to determine the 

 gross anatomical distribution of the various chromaffin organs. 



Besides the "parotid gland," pieces of the dorsal skin, kidney, adrenal, testis, and 

 sympathetic ganglia were prepared and sectioned. All of our material was obtained from 

 healthy adult animals brought to Baltimore from the region about Montego Bay, Jamaica. 

 British West Indies. 



It is a pleasure to express here our gratitude to Professor John J. Abel, of the Depart- 

 ment of Pharmacology, who very kindly gave us the toads which we have studied and 

 whose advice and assistance have been of great value in the preparation of this paper. We 

 wish to thank also Airs. F. R. Schultz for the drawings with which this paper is illustrated, 

 and we are indebted to Mr. Kurd, of the Anatomy Department, for the photomicrographic 

 illustrations. We wish here to acknowledge our obligation to him. 



We have also had the privilege of examining some sections of the poison-glands of this 

 same toad which were made by Dr. E. B. Wood, while a student here in 101 1-12. These 

 sections, which we found very useful in confirming some of our findings, were presented by 

 him to the Johns Hopkins University and are now in the demonstration collection of t he- 

 Department of Anatomy. 



