356 Efl-a Funk Miihse. 



produce a granular secretion which helps to loosen the molt from 

 the underlying stratum. 



2. The so-called cutaneous glands arise as l^uds in the germinating 

 stratum of the epidermis. The first gland buds arise just as the 

 tadpole has passed its most typical aquatic form. From this time 

 on during the life of the toad, new ones arise in a similar manner. 



3. Very early the bud becomes differentiated into neck, collar and 

 acinus. As a gland enlarges, it pushes deeper and deeper into the 

 cutis, but a direct connection is not established between the cutis and 

 the glands. Before the first glands reach maturity, new glands arise 

 and develop, and even a third series may be developed. A very com- 

 plete series of stages arranged in two or three strata may be found 

 between the earliest stage and the mature glands. The climax is 

 reached by the large mature glands, whose granular secretion is 

 irritating or poisonous in its effects on other animals. 



4. The elements of all the parts of a mature gland appear in the 

 very early stages, but they increase in size and number as develop- 

 ment proceeds. The shape of the acinus and collar gradually changes 

 as the lumen fills with secretion. 



5. The wall of the acinus of a mature gland consists of a matrix 

 in the periphery of which are imbedded smooth muscle fibers meri- 

 dionally arranged. Attached to the lumen surface of the matrix 

 is the epithelium, which for the most part consists of naked nuclei, 

 irregularly arranged. 



6. The collar and neck of the mature gland consists of two con- 

 centric zones of cells radially arranged. x\t the outer limit of the 

 collar the cells of both zones are arranged in a pecidiar cog-whecl- 

 liJce structure. The outer ends of the more distal muscle fibers, 

 which have extended from the wall of the acinus in among the cells 

 of the outer zone of the collar, reach to the cog-wheel. An effective 

 attachment for the action of the muscle fibers is thus established. 



7. The duct of the mature gland is slit-like and irregular in shape 

 in the region of the epidermis. Through the remainder of the outlet 

 it is more or less circular in form, and is often closed for part of 

 the way. 



8. The first gland buds that arise in the epidermis of the tadpole 



