ISO PROTOPLASM 



The structural relations described can naturally be 

 observed most clearly in isolated axis-cylinders, such as one 

 frequently obtains by teasing. On the surface of such 

 cylinders there occasionally appeared to be present a radiate 

 alveolar layer consisting of a single layer of meshes, which 

 in surface view was distinguished by the simple net-like 

 character of its meshes from the fibrous meshwork of the 

 enclosed portion. Since, however, I only rarely observed 

 this quite plainly, I do not lay any stress on the point. 



On the other hand, I was frequently able to convince 

 myself quite definitely in such isolated axis-cylinders that the 

 apparent fibrillae sometimes divide, or rather, that in places 

 where the axis-cylinder becomes thinner (see Plate VIII. 

 Fig. 1, &), the fibrillee decrease in number. This seems 

 perfectly natural if we regard the substance of the axis- 

 cylinder merely as a modification of the ordinary net-like 

 meshwork of protoplasm. The greatly narrowed portion 

 of an isolated axis-cylinder, drawn in Fig. 1, &, corresponds 

 most probably to the region of a ring-like constriction, where, 

 in fact, according to most observers, the axis-cylinder be- 

 comes transitorily narrowed. With reference to this point, 



muscle cells, are all to be set aside as artificial products, since, according to 

 his view, the muscle fibril is a completely homogeneous secretion-product of 

 the protoplasm, which has nothing to do with its structure. 



He even goes so far in this respect as to declare that ' ' Biitschli's methods 

 of investigation present every possible means of producing an alveolar structure 

 in an otherwise homogeneous colloid substance by swelling." I do not call 

 to mind that I have employed any other methods than the usual ones, or than 

 those used, at all events, by Apathy himself. 



To interpret as artificial products, resulting from the swelling of colloid 

 substances, the structures described by Schewiakoff and myself in the con- 

 tractile elements of Arthropod muscles, certainly astonishes me greatly. Such 

 an idea would not be very much out of place as regards the irregular structures 

 of ordinary protoplasm ; but to apply it to such regular structures as 

 those of the contractile elements is somewhat strange. Without, however, 

 entering here into a further defence of our discoveries against Apathy's 

 assertion, I may be permitted to refer to Schafer's work (1891, 1892, and 1893), 

 and which at any rate confirms independently a great part of our observa- 

 tions, even if it interprets what has been seen in a different way. 



A discussion of the conceptions as to protoplasm expressed by Apathy in 

 the memoir referred to, and of the attacks which he takes the opportunity of 

 directing against my theory, may, I think, be omitted, since the author's course 

 of reasoning remains unintelligible to me in many ways, besides that many 

 points emphasised in it appear to me of quite subordinate importance. 



