The Cutaneous Gluiuls of Comniou Toads. 355 



warts. On the ventral surface, and between the warts of the dorsal 

 surface, they only occur occasionally (Fig. 15). Excepting the 

 parotids, the warts and hence the mature glands, vary in number 

 and their exact distribution is not constant for the species. The 

 same is true of mature glands which occur singly. This is con- 

 clusive proof that the so-called poison gknds , i. e., the mature glands, 

 are not destined to arise in identical regions of the skin of all indi- 

 viduals of the species. 



The small glands are more numerous than the mature glands. 

 In either the warts or in the ordinary skin of the back, they are 

 about proportionate to the number of mature glands occurring in 

 the region. In the ventral skin, the ratio between the younger 

 stages and the mature glands is considerably greater. The younger 

 stages are larger than a similar stage in the dorsal surface. The 

 epithelial cells of many of these glands seem to have been arrested in 

 their development, while the acinus continues to enlarge (Fig. 15). 



Proofs from warts with degenerate glands and from growing wiarts. 

 Certain warts consist of a quite uniform inner battery of glands, 

 which show no degenerate glands. The outer battery is then quite 

 uniform in size, structure and apparent age, and there exist no 

 transitiorual forms (Figs. 13, 14). On the other hand, there are 

 Avarts which show degenerate glands in certain areas, or quite gen- 

 erally in the lower part of the wart. The glands of the outer battery 

 are in these areas varied in their appearance, transitional forms 

 exist, and even the mature glands may be very different in size and 

 shape (Figs. 23, 24, 57, 58). 



Certain warts seem to be enlarging by the addition of glands, 

 and show some of the previous conditions, especially as to the ir- 

 regidarity of the inner series (Figs. 21, 22), 



Conclusions. 



1. There are present in the epidermis many beaker cells, each a 

 one-celled gland, the mouth of whose slender neck opens between 

 the transitional and the molt strata. They are found in the epidermis 

 of all regions of the body, and may occur in large numbers. They 



