UNIVERSITY OF CALIFORNIA l-U BLICATIONS 

 ZOOLOGY 



Vol. 1, No. 7, pp. 227-268, Pis. 20-24 June 1, 1904 



THE STRUCTURE AND REGENERATION 



OF THE POISON GLANDS 



OF PLETHODON. 



BY 



C. 0. ESTERLY. 



It has long since been held that the skin glands of both the 

 Urodela and the Anura are of two kinds. This distinction was 

 first made by Ascherson '40 in an investigation of the glands in 

 the web of live frogs, and was based upon the size, shape, and 

 location of the glands without regard to function or microscopic 

 structure. That the skin of Amphibians secretes a substance 

 other than the well-known mucus, and clearly poisonous, has 

 beeu shown by many physiological and toxicological experiments 

 and investigations (Albini '5(3; Boulenger '92; Calmels '83; 

 Capparrelli '83; Dutarte '89; Gratiolet and Cloez '51-'52; 

 Hubbard '03; Phisalix-Picot '00), and the facts gained from 

 experiment are upheld as far as possible by histological evi- 

 dence. Microscopic examination shows that there is more than 

 one kind of gland. (Ancel '02; Coo-hill '99; Eberth '69; 

 Eckhard '49; Engehnann '72; Hensche '56; Leydig '76 a; Pau- 

 licki '85; Phisalix-Picot '00; Sdmltz 89; Seeck '91; Stieda '65; 

 Szczesny '67; Wiedersheim '86). These have generally been 

 distinguished as granular (Kornerdriisen) and clear, according 

 to the appearance of the secretion contained in them, the former 

 having been almost unanimously looked upon as making the 

 poison series, the latter the mucous series. The suggestion has 

 been made, however, that the various glands are only the young 

 and old stages of one sort of "land (Junius '98), and this ques- 

 tion will receive further consideration in the present paper. 



