THE HYALOPLASM OF LEYDIG 281 



memoir of 1885 (p. 43). It runs thus : " We know that the 

 hyaloplasm contains throughout an abundance of water in 

 fact, as far as the perceptions of our senses are concerned, 

 hyaloplasm and water may run into one ; they form, if we 

 may assist ourselves with the expression, a solution. Where, 

 then, is the line to be drawn between water and hyaloplasm, 

 a line which it is nevertheless necessary to assume ? " 



In spite of this evident lack of any idea at all definite 

 as to the nature of the hyaloplasm, Leydig did not hesitate 

 to regard it both as " the primary motile substance " 

 (p. 152) and also as the nervous, etc., although he was not 

 even quite certain whether lymph might not be identical 

 with hyaloplasm and with the homogeneous nerve sub- 

 stance, which was also supposed to be merely hyaloplasm. 

 Since Leydig's assumption, as has been pointed out, was 

 based principally upon the supposition that the axis- 

 cylinders consisted of such homogeneous and structure- 

 less hyaloplasm, for which very reason the hyaloplasm was 

 supposed to be the real nervous and generally active 

 substance, this view of course falls to the ground, when 

 it is proved that the axis - cylinders possess just the 

 same honeycombed structure as the rest of the protoplasm. 

 Even with the modification which ISTansen (1887) has given 

 to Leydig's view, the latter is no longer tenable, since, as we 

 saw, the assumption that the axis-cylinders are composed of 

 continuous hyaloplasmic nerve tubules is incorrect, because 

 the hyaloplasm, or in our terminology the enchylema, is 

 really discontinuous, and distributed in the substance of 

 the axis-cylinder in the form of numerous chambers or 

 alveoli separated by delicate partitions. If, however, this 

 view is correct, it seems absolutely necessary to consider the 

 substance of the framework as the substratum of nerve 

 conductivity, for it alone extends continuously through the 

 axis-cylinder, and is therefore in a position to be instrumental 

 in conduction. The arguments brought forward by Pfliiger 

 (1889) against Leydig's view seem to me also important. 

 Pfliiger remarks that this assumption is improbable from the 

 fact that the nerve fibres are only stimulated by currents 

 directed longitudinally, and not by those directed transversely, 



