334 ■ Effa Funk Muhse. 



than others; that the large poison glands are more completely dif- 

 ferentiated toward a special function. 



Secretion and luhen expelled. Under proper conditions, the secre- 

 tion, which is produced by the cutaneous glands of Batrachians, 

 comes to the surface of the animal. The skin of a toad, which has 

 in no way been disturbed, is dry. If it is roughly handled, some 

 of the cutaneous glands expel a colorless fluid and the skin becomes 

 moist. Under a powerful stimulus a milky secretion oozes through 

 the ducts to the surface in the form of small drops. It is probable 

 that in nature, only the most severe shock or torment by a natural 

 enemy causes the expulsion of the milky secretion. The toads, which 

 have been dealt with in this investigation, have in no case expelled 

 it short of chemical, electrical or severe mechanical stimulus, or only 

 after the head has been severed from the body. If the stimulus, 

 e. g., electrical, is localized, only the glands from the stimulated 

 region are discharged. The relation of the transparent and the thick 

 milky secretions to the glands will be discussed later. As far as con- 

 cerns this investigation we will accept it as an established fact that 

 at least the milky secretion has an irritating effect on mucus mem- 

 branes. Further, that on certain small animals of other species it 

 is poisonous and even fatal in its results. Investigations of a chemical 

 and experimental nature have shown this to be true of the secretion 

 from a number of Batrachians. (Gratiolet and Cloeg, '52, Calmels, 

 '82, Phisalix, '00.) 



Origin of glands in the larva. The development of glands in the 

 larva has been followed in a few Batrachians, notably the sala- 

 manders. With one exception (Phisalix, '00) the more recent writers 

 (Maurer, '95, Ancel, '01) agree that they come from the ectoderm. 

 Here and there in the lower cell layer of the primitive epidermis 

 of the tadpole, a single cell becomes differentiated. Eapid cell 

 division follows and a gland bud, i. e., a small solid mass of cells 

 is soon established. This cell collection pushes do\vn into the cutis, 

 retaining a connection with the epidermis. At the point of connection 

 the future duct is developed and a lumen soon arises in the acinus. 

 I have observed gland buds in the toad tadpole, Avhose body length 

 was 8 mm. (Fig, 6). The hind legs had at this stage reached a 



