432 TEMP. -MAJOR H. M. EVANS ON 



tubes which converge at the base, providing a passage for the 

 blood capillaries, which supply the connective tissue suri'ounding 

 the gland." 



" On making transverse sections of the sting and putting them 

 under the microscope, we see that the ventral furrows are 

 occupied by a glandular mass of a more or less triangular shape 

 with the corners rounded off. It is composed of a great many 

 cells of various sizes and shapes (■2-"4 mm. x510), often joined 

 to one another to form true glandular follicles, which measure 

 •7-l'5 mm. x510; the connecting and surrounding tissues are 

 rich in blood-vessels and communicate with the sheath of the 

 sting. Towards the apex the gland gets smaller, the cells 

 become less numerous and smaller and are surrounded by much 

 connective tissue, with which they gradually merge." 



" This gland is similar to that which is observed in the genus 

 Scov'pcena and in the greater number of other poisonous fish. It 

 should be considered as a cutaneous gland. The dart is merely 

 an arm of defence. It is united to the tail by strong ligaments 

 and muscles, which only, however, permit a small lateral move- 

 ment. The emission of the poison takes place in a very simple 

 manner. The sting introducing itself into the wound, the sheath 

 is drawn back towards the base and presses on the gland which 

 thvTS emits a poisonous liquid, which flowing towards the narrow 

 apical groove thus inoculates the wound." 



Part II. Observations on Serial Sections. 



I am in agreement with Dr. Porta as to the position and 

 general triangular outline of the gland. I have not personally 

 examined the poison-organ of Scorpmna, but the elongateVl com- 

 pressed cells pictured by Bottard in the grooves of the spine of 

 Scorpcena are of the same type as the gland-cells of both 

 Trachinus draco and vipera, and according to that authoi'ity the 

 poison-gland of Scorpcena is a less developed type of the gland 

 found in the Weevers. Having myself made many sections of 

 the glands of both the Gi-eat and Lesser Weevers, I can state 

 with assurance that the glandular structui'e found in Trygon is 

 of a totally different type : in fact, there are many points in its 

 structure of a unique character, and the arrangement of the cells 

 requires cai'eful examination. The gland consists, for the most 

 part, of a fine mesh, within the interstices of which are groups of 

 small cells with a vacuolated protoplasm. These cells are grouped 

 together in regular follicles. 



These follicles in other parts are entirely filled with secretion, 

 so that you have a cystic appearance, a distended cavity, lined by 

 a layer of flattened cells. The external margin of this glandular 

 mass shows a well-marked layer of pigment-cells, a,nd external to 

 this are several layers of rounded epithelial cells, Avhich, however, 

 are frequently detached in the sections, as shown in text-fig. 2. 



If we could understand the origin and relations to other parts 



