352 Effa Funk Miihse. 



wall of the mature glands (Figs. 51, 52). The appearance of the 

 cytoplasm in the cells is exactly similar to the secretion in the 

 lumen. This is evidence that the granules are produced by the same 

 nuclei that furnish the liquid secretion. If these are poison cells 

 they must necessarily have remained latent for a long period. On 

 the other hand, it is possible that under certain conditions, while 

 the nuclei are secreting, a difference between the density of the 

 old and new secretion may cause the new secretion to be limited 

 to a small area for a time. If this is so, these are sacs of poison 

 rather than true cells. 



Life history of the one hind of gland. Since the mature glands, 

 occurring in large numbers in the warts, pour out their secretion 

 at times, the questions arise: how is the secretion perpetuated and 

 how are the glands replaced when worn out or destroyed ? 



Literature. Heidenhain and Esterly have each stated concerning 

 certain salamanders, that a gland bud is present in the neck or 

 collar of every poison gland. When the latter is emptied of its 

 secretion, the bud begins to grow. Heidenhain states that he observed 

 intermediate stages and that some cells of the ingrowing gland were 

 granular in nature. Esterly says that the bud is always mucus, 

 but he has never observed transitional stages between the germ and 

 the poison glands. I have observed an ingrowing gland in different 

 stages of cutaneous glands in Amblystoma jeffersonianum, but not in 

 the case of the toads. 



Schultz says that epithelial cells of the poison glands increase 

 by mitotic division, and that only a few cells reach their development 

 at the same time. Drasch states that completely emptied poison 

 glands are replaced by small ])oison glands which grow rapidly. 

 Junius suggests that the old glands are probably replaced by entirely 

 new glands. 



Mme. Phisalix states that emptied glands, refill, Weiss says that 

 the protoplasm of the inner part of the epithelial cells furnish the 

 secretion of the poison glands. He further says that the poison 

 glands of the toad, which have been artificially stimulated to ex- 

 haustion, refill completely in from 24 to 36 hours. He considers 

 that this opposes the idea that the secretion arises through cell 

 growth and succeeding dissolution. 



