30 DR. KLEIN. 



with an oblong nucleus, containing a relatively large 

 nucleolus. The whole of this part of the cell-body is destitute 

 of pigment ; and the nucleus itself is only to a small extent 

 covered with pigment-granules. Furthermore, it may be 

 seen that the processes also, both those which appear with 

 a low magnifying power to terminate abruptly and those 

 which are indistinctly defined, can be traced outwards far 

 beyond the limits of the pigment, and that the processes of 

 two adjacent pigment-cells are connected together just in the 

 same way as has been described in the case of the non-pig- 

 mented cells. In those parts which are free from pigment 

 both the processes and the body of the cell appear pale and 

 finely striated, as if composed of fibrillar. It is, in fact, 

 noticeable that in those parts where the pigment granules 

 lie less closely together (as is generally the case in 

 the fainter parts), the pigment-granules are arranged in 

 rows, as if placed simply one behind another between the 

 fibrils. Occasionally, one or two such rows of pigment- 

 granules may be found imbedded in a comparatively broad 

 process, and extending from one cell to another ; or, on the 

 other hand, a very broad process may be seen, with a narrow 

 middle zone filled for a short distance only with thickly 

 crowded pigment-granules. Moreover, in those pigment-cells, 

 which have, as it is usual to say, completely "retracted their 

 processes," and thus assumed the form of spherical or 

 oblong black masses, it is not hard to make out that the 

 pigmented mass by no means constitutes the whole cell, but 

 that there exists besides this — perhaps a part of the body of 

 the cell — certainly a number of broader or narrower pro- 

 cesses which are branched, pale, and more or less distinctly 

 striated. 



The objection may be made that these appearances (which 

 I have just described from a gold preparation) are not suffi- 

 ciently convincing to establish the conckisions I have drawn, 

 viz. that the pigment-cells are branched cells, which retract 

 the pigment-granules, but not the processes ; that the pig- 

 mented portion gives no decisive indication of the magnitude 

 of the cell-body or of the shape and size of the processes ; 

 and again, that the pigment-granules are arranged between 

 the fibrillae of the protoplasm of the cell. This objection 

 may be met hy the following observation : 



A nictitating membrane was carefully prepared with all 

 due precautions, and placed under a cover-glass Avith a drop 

 of humor ciqueus, the pressure of the glass being removed by 

 the well-known expedient of placing thin strips of paper by 

 the side of the object ; the whole was then closed at the 



