254 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



the nucleus visible, being left behind in the basal part of the cell 

 surrounded by a scanty amount of apparently unaltered protoplasm. 



(f) Glavate Cells. — These gigantic cells, first described by Leydig 

 as ' Kolbenzellen,' enter very largely into the formation of the epi- 

 dermis in Amiurus, as indeed into that of many fresh-Water fishes, 

 such as the eel, burbot, and tench. They have also been examined 

 with care by Pfitzner in the skin of salamander larv*, and are de- 

 signated by him ' Leydigsche Schleimzellen.' 



It is with some difficulty that one succeeds in getting ' clavate ' 

 cells (as they may be termed) isolated. After twenty-four hours in 

 Midler's fluid the other epithelial cells fall readily asunder, but the 

 clavate cells are generally surrounded by a sort of capsule formed 

 of the neighbouring ordinary epidermal cells. These may be in time 

 brushed off, but they invariably leave their trace upon the outer 

 surface of the wall of the clavate cell in the form of a reticular 

 sculpture. When freed from the adherent cells the clavate cells of 

 Amiurus are found to vary considerably in their form ; the smaller 

 ones are rounded or oval, and this is the case also in young fish, but 

 in adults the proximal end tapers and frequently divides extending 

 down towards the corium, but getting no nearer than the row of 

 palisade cells between which the divided ends frequently dovetail. 

 The clavate cell has a distinct wall, which, like the wall of other 

 epidermal cells, is merely the outermost layer of the protoplasm, 

 acquiring a certain amount of independence with the age of the cell. 

 In small cells and in young forms I find the clavate cells filled with 

 a granular substance which has a certain refractive aspect, and con- 

 tains one large or two smaller nuclei in various stages of separation 

 from each other. In preparations from adult skin the contents of 

 the clavate cells are very different ; vacuolation has set in either at 

 one or both ends of the cell, generally at the proximal end first, and 

 the vacuoles which are occupied by a colourless fluid are separated 

 by a network of protoplasm still in contact with the rest of the 

 granular substance. Also in the neighbourhood of the nucleus doe& 

 vacuolation take place, resulting in a clear area through which only 

 a few protoplasmic fibres straggle from the nucleus to the granular 

 matter. Vacuolation proceeds till very little of the granular matter 

 is left, but that generally assumes a somewhat crescentic outline at 

 the broad end of the cell, forming a sort of cap — ' Kappchen ' — to 

 the rest of the contents. By the time this process has advanced so^ 



