TENTACLES OF BLENNIUS GATTORUDINE. 301 



bodies o£ n fairly constant, somewhat bottle-shaped form. The mass of the 

 cell appears to be composed of fine, highly refractive granules ; it stains 

 rather deeply with carmine, and appears uniformly greyish after tieatment 

 with osmic acid. In the centre of this granular mass there is a large nucleus, 

 which often appears to consist of two halves ver}^ closely apposed. This 

 peculiarity does not, however, appear to be constant. The double nucleus 

 may be seen in my figures 2 (A, n') and 9 (A). At the outer end of the cell 

 there is always a little clear, cup-shaped hollow, which in my preparations 

 always seen)s to be open to the exterior [fig. 10 (c.) and 9 (o.)]. According 

 to Schulze, this hollow, in the " Kolben " of Petromyzon, varies considerably 

 in size and position. In some cases he found it as a mere space in the cell, 

 with no external opening. In others it not only had an opening at the outer 

 extremity of the cell, but might even extend inwards as an elongated tubular 

 cavity, tapering to a point towards its proximal end. This appeaiance I have 

 never observed in my preparations. Schulze is of opinion that the form with 

 closed cavity is an early stage, and that the cavity afterwards acquires an 

 opening and pours a secretion out on the surface of the skin. He finds fat- 

 globules sometimes present in the cavity, but does not seem certain whether 

 these may not be pathological. According to M. Schultze [3] (as quoted by 

 Schulze), the " Kolben'^ of Petromi/zon often .'ippearto be in close connection 

 with perpendicular strands of connective tissue imn;ediately below the cutis, 

 and these strands often contain a dark fibre which may possibly be a nerve- 

 fibre. He also finds, as does F. E. Schulze, that the Kolben themselves 

 show certain cross-striations, caused by alternate layers of donbly and singly 

 refractive substance, comparable to the appearance of striated muscles. 



M. Schultze therefore draws the conclusion that the Kolben are probably 

 " nervose Endapparate muskuloser Natur.^^ 



F. E. Schulze, however, points out that neither the cross-striations nor the 

 intimate connection with the cutis are constant for all fishes in which 

 '• Kolben" are found. In Petromyzonfiuviatilis and the Eel, he says, all the 

 " Kolben " stand on the cutis ; but in other fishes examined by him (Siluriis, 

 Cobitis, Tinea, and Leuciscus) they may occur at all levels in the epidermis 

 and separate from the cutis. Even in another species of Lamprey, described 

 by H. Miiller, both these peculiarities of the " Kolben " are absent. Schulze 

 therefore remains undecided as to the nature of these cells, but thinks they 

 are perhaps comparable with the sebaceous glands of mammals, their 

 substance breaking down to form latty matter, wdiich is discharged as a 

 secretion on the surface of the skin. He thinks that normally the " Kolben " 

 migrate to the surface to perform this function ; in Petromyzon and the Eel, 

 where they never lose their connection with the cutis and have no actual 

 opening on the exterior, their secretion probably finds its way out between 

 the outer cells of the epidermis. He is also of the opinion that their 

 apparent muscular structure may be for the expulsion of the secretion. 



