THE SKIN. 273 



bands. These connecting cords sometimes divide and anas- 

 tomose with each other, forming a sort of network between the 

 cells. In this case, the dark spaces do not always extend 

 from one cell-body to another, since they may correspond to 

 the space between anastomosing filaments. These bands are 

 therefore not the prickles of adjoining cells, which interlock 

 with each other, but are true connecting filaments between 

 cells of a common origin, and which iiave not yet become sepa- 

 rated from each other. The connecting bands or fibres gradu- 

 ally diminish in length and thickness from below upward, and 

 finally cease to exist when the granular layer is reached. 



The spaces between the bands are filled with an inter- 

 cellular albuminous substance, and they may be regarded as 

 minute channels for the conveyance of nutriment to the cells 

 of the epidermis. The above view of the " prickles" corre- 

 sponds very closely with that held by Dr. Martin, and differs 

 from that of later observers, who maintain that the dark lines 

 are connecting bands, and the light lines the spaces between 

 them. 



Owing to the close union of the Malpighian elements it is 

 very difficult to isolate them. Perhaps the best way to accom- 

 plish this result is by long immersion in iodized serum. Fig. 

 117 represents a cell isolated in this manner. Here 

 the bands have been torn apart and the cell-surface is 

 studded with thorn-like projections. Hardening in 

 chromic acid, with subsequent boiling in a moderately 

 strong solution of potash, causes a separation of the 

 mucous layer from the corium and a falling apart of the rete 

 cells (Biesiadecki). The structure of the corpuscles, however, 

 can be best studied when their normal relations with each 

 other are preserved. Yariations in the number of cellular lay- 

 ers are of normal occurrence in the rete, although this portion 

 of the skin shows the least variation as regards its thickness. 

 The arrangement of the elements in these different strata is the 

 same in all parts of the body, and appears to be independent 

 of the thickness of this layer. 



As regards the direction of the long axes of the cells there 

 is a gradual passing from the perpendicularly seated cells of 

 the first layer to the horizontally lying cells of the uppermost 

 >w. The lower surface of the rete adapts itself to the upper 

 mrface of the corium, and between the papillae projects down- 



