ANATOMY OF THE POISON GLAND OF HELODERMA. 



21 



which they follow to all parts of the organ. Most of the blood leaves the gland 

 by a vessel which extends along its entire ventral edge. The relations of this 

 vessel are essentially those of the submental vein of mammals. At its hinder 

 end it is joined by the inferior labial vein. The common trunk thus formed is 

 the facial vein. This is continued backward along the sides of the face, finally 

 joining the internal jugular. Near its anterior end the submental vein gives 

 off a smaller vein which curves mesially under the lower jaw and joins a vein, 

 evidently the anterior jugular, which lies on either side of the trachea (fig. 5). 

 Some of the veinlets in the upper portion of the gland appear to communicate 

 with the inferior labial vein. 



FIG. 6. Ventral view of approximately half of head, showing arte- 

 rial supply of poison gland. Drawing partly diagram- 

 matic; approximately natural size. 



1. Poison gland, turned outwards. 



2. Mandible. 



3. Inferior dental foramen with inferior dental artery and 



nerve. 



4. Pterygoid bone, outer half removed. 



5. Quadrate. 



6. Internal carotid artery. 



7. External carotid artery. 



8. Lingual artery. 



9. Posterior auricular (?) artery. 



10. Common carotid artery. 



11. Left aortic arch. 



11 



HISTOLOGIC STRUCTURE. 



For the minute study of the gland, pieces were fixed in various fluids, but 

 the most satisfactory fixation was obtained by the use of Bensley's modification 

 of Kopsch fluid. (See "The finer structure of the glandula submaxillaris " 

 by B. A. Cohoe, in Amer. Journ. of Anatomy, vol. vi, No. 2, 1907, p. 171.) 

 This fluid was especially favorable for the preservation of the granules in the 

 secreting cells, the other fluids used being rather defective in this respect. 

 The sections were stained mostly in Benda's iron hematoxylin, followed by 

 eosin, erythrosin, or Bordeaux red. Some sections were doubly stained in 

 safranin and gentian violet. 



