330 ANNALS NEW YORK ACADEMY OF SCIENCES 



introduced into Bermuda about 1885, where it has thriven to such an extent 

 as to become a nuisance. Owing to the facilities of investigation upon this 

 largest living Anuran and because of the economic aspects of its poisonous 

 character, it has been an object of especial attention to the New York Uni- 

 versity Biological Expeditions at the station on White's Island, Bermuda. 

 Experiments have shown that the poison is very like "curari" in its effects. 

 A subcutaneous injection of moderate doses into a dog causes convulsions 

 followed by death in about an hour. 



The skin of the dorsal side of Bufo aqua is characterized by large warts 

 and the parotoid gland is enormously developed. The poison is exuded 

 from these warts, and most abundantly from the parotoid when the animal 

 is irritated. Besides the poison, which is thick and milky, a colorless, non- 

 poisonous mucous common to all amphibians is exuded from all parts of the 

 skin. These secretions are elaborated in simple alveolar skin-glands of 

 which there are two t\'pes. The glands of the first type — small clear mu- 

 cous glands — are distributed throughout all regions of the skin ; those of the 

 second type — the larger granular poison glands — occur only on the dorsal 

 aspect of the head, trunk and limbs, and are grouped in the parotoid and 

 the warts. 



The physiological processes that take place within the cells forming the 

 epithelium of the mucous glands (first t}^e mentioned above) are those 

 typical of ordinary glandular epithelium. In Bufo aqua these glandular 

 cells after a period of activity certainly go to the ground. The glands them- 

 selves, after a period of activity, degenerate and are resorbed. 



The processes involved in the formation of the poison, and the method of 

 regeneration of poison glands has been investigated in various Urodeles, 

 but we have been able to find few, if any, references to investigations on the 

 glands in toads, in which the poison function has become most highly de- 

 veloped. The poison glands of Bufo aqua are ovoid in shape and in the 

 parotoid region attain a size of 7 mm., whereas the mucous glands are mi- 

 croscopic in size. A poison gland consists of an outer membrana propria, 

 a layer of smooth muscle fibers and an inner simple columnar epithelium. 

 The neck of the gland in B^ifo aqua gradually merges into a wide duct pass- 

 ing out perpendicularly to the surface of the skin. Around the mouth of 

 fully grown poison glands there is a group of from three to six small glands 

 which have arisen by invaginations of the INIalpighian layer of the epidermis. 

 The epithelial cells of the poison glands, Avhich develop large characteristic 

 granules within the cytoplasm, grow to a large size and finally disintegrate. 

 The substance of the cells thus becomes the poisonous secretion which 

 comes to fill the lumen of the gland. Now the muscular layer develops 

 greatly and the glands are gradually emptied. At this point one of the 



