POISON-GLAND OF THE COBRA. 17 



Immediately after the glands had been removed they were 

 divided into fragments and placed in the following fixing 

 solutions : — 



Bouin's liquid (picro-acetic , formalin). 



Champy's liquid (bi-iodide of mercury, formalin). 



Regaud's liquid (bi-chromate de potasse, formalin). 



Benda's liquid (acide osmique — acide chromique). 



Some glands were fixed whole in formalin, in order to 

 study the microscopical anatomy in its entirety. After fixa- 

 tion the fragments were immersed in paraffin and cut into 

 sections of 1/200 mm. or 1/400 mm. in thickness by Minot's 

 microtome. To stain the sections I utilized the following : — 



Hematein-eosin. 



Heidenhain's ironized hematoxylin. 



Prenant's eosin, vert lumiere, ironized hematoxylin. 



Safranin, green. 



Benda's krystall violet. 



II. — Microscopical Anatomy. 



If a complete section of the whole length of the poison-gland 

 and its excretory duct be examined under low power one 

 immediately observes that two kinds of substances can be 

 distinguished, one a connective and peripheral substance, the 

 other, and most important, a glandular and central substance. 



There are, therefore, in a poison-gland two things — first the 

 fibrous capsule, and within the fibrous capsule that most 

 interesting part, viz., the part where the poison is formed. 



The complete longitudinal section of the poison-gland is 

 bottle-shaped (fig. 1), the neck part of which becomes the 

 excretory duct. The fibrous capsule is thickest in the broad 

 part of the gland and becomes thinner as the gland narrows. 

 Here and there we see that the capsule forms a connective 

 network, in which are found sections of blood-vessels, lymph- 

 vessels, and nerves. The fibrous structure and the lymphatic 

 spaces are particularly noteworthy. 



The central portion, which we have seen to be alone 

 glandular, is divided into two quite different regions. First, 

 there is the bulky part occupying the body of the bottle 

 which is, properly speaking, the poison gland. Secondly, 



D 6(2)] 3 



