OF THE VENOM OF THE RATTLESNAKE. 



13 



softness of the intermediate tissue, I have found great difficulty in tracing the 

 smaller ducts, Fig. 7, h. Soubeiran^ describes them in the Viper, as terminating in 

 minute pouches of amorphous matter. Rjmer Jones (article "Reptilia," Cyclopedia 

 of Anatomy and Physiology) also speaks of the ducts dividing, to form smaller 



Fig. 7. 



MicKOScopicAL Structure of the Venom Gland. — a, secernent cojca ; b, small ducts. 



tubes, on vphich are finally developed secernent coeca, Fig. 7, a, like those of the 

 ordinary salivary glands. In perfectly fresh specimens, these coeca can sometimes be 

 made out. They are lined with pale tessellated and nucleated rounded epithelia, 

 and are commonly filled with amorplious and granular matter, Fig. 7, a. The 

 epithelia in question are very easily altered, and in glands kept for a few hours in 

 summer, are scarcely to be recognized. The smaller ducts are lined with a pale 

 and narrow columnar epithelial cell, Fig. 7, h. The cavity at the base of the gland, 

 as well as the main duct which connects with the fang, are lined with large pave- 

 ment-epithelial cells, which possess distinct nuclei. Fig. 8, a. This form of epithelia 

 is not usually encountered in this position, in homologous glands, whose ducts are, 

 on the contrary, covered internally with columnar epithelia. Outside of this cellular 

 layer, the poison duct is made up principally of white fibrous tissue, with a small 

 proportion of very fine fibres of yellow elastic tissue. The walls of the duct are 

 provided throughout with an abundant supply of bloodvessels. 



Just above the line of the lip, and consequently at the base and outer side of 

 the maxillary bone, the duct, in turning to descend this bone, becomes abruptly 

 larger, for a distance of a line, or a line and a half. Fig. 6 B, c. Its color at this 

 point is also a little redder than the rest of the duct. Beyond this point, the duct 

 again becomes smaller. If now a probe be introduced into the duct, and its whole 



' J. L. Soubeiran, De la Vipere Paris, 1855, p. 47. 



