8 Journal of Comparative Neurology. 



nuclei are adjacent to the horny layer the ectal division, the 

 others the ental division. It will be seen that the nuclei of 

 these ectal and ental cells differ in arrangement and in structure, 

 thus perhaps portending a difference in function. The ental 

 nuclei are of loose, reticular texture and lie with their long axes 

 parallel to that of the cell. The ectal nuclei are denser and lie 

 transversely in their cells. At this stage, then, the epidermis 

 is made up of three kinds of cells; namely, the horny layer, 

 containing much flattened cells, and the Malphigian layer which 

 consists of ectal and ental cells serrately arranged. 



The cutis vera, or corium, consists in the second stage of a 

 single band of closely compacted connective tissue fibres and 

 has a wavy appearance. Just before the metamorphosis there 

 is developed a superficial layer. This is a loosely meshed and 

 much pigmented layer and ultimately forms a support for the 

 glands. At this same time may be seen the deepest layer of 

 corium. It lies just beneath the dense wavy layer and contains 

 a delicate mesh-work of connective fibres, nerves and blood-ves- 

 sels. By means of this layer the corium is connected with the 

 underlying organs. 



No glands or indications of glands are seen until just before 

 the metamorphosis. At this time the nuclei of the ental cells 

 of the Malphigian layer become more granulated and at certain 

 places they divide rapidly, forming nests of small dense cells, 

 from which the glands are formed. These bunches of cells push 

 aside the loosely connected superficial layer of the corium and 

 the fibres of connective tissue now are crowded together so that 

 they have the appearance of closely compacted bundles running 

 at right angles to the corium. Through these the nerves now 

 reach the epidermis. (Figs. 2 and 6.) 



At a stage somewhat earlier than that just alluded to there 

 may be seen in the ectal cells of the Malphigian layer peculiar 

 skein-like bodies (Figs. 3, 4). They bear some resemblance to 

 nerves and indeed have been mistaken for them. Pfitzner 1 in 

 frog larvae of about the same age as those here described ( i. e. , 



^ervendigungen im Epithel. Morph. Jahrbilch., Bd. VII, 4 Heft, 1882. 



