28 BULLETIN OF THE 



('89, p. 168) could not distinguish fibres in the cones of Alpheus, al- 

 though, like Kingsley, he admits that his failure may be due to the 

 method which he used. Eelative to nerve-terminations, the evidence 

 which the work of these two investigators presents can scarcely be called 

 critical, and I therefore hold to my former conclusion, namely, that the 

 fibres which according to Patten represent the nerve-terminations are 

 in reality not nerve-fibres at all. 



After having reached this conclusion, I was naturally led to look 

 elsewhere for the true nerve-fibres. It occurred to me that, in order to 

 be certain that I was dealing with nerve-fibres, it was safer to begin 

 studying them in regions where their identity was beyond question. I 

 therefore examined maceration-preparations of parts of the larger nerves 

 from the lobster's body. These nerves were readily resolved into a 

 number of fibres, which in transverse section were enormous when 

 compared with such fibres as the axial nerve-fibre figured by Patten 

 ('86, Plate 31, Pigs. 72, 74. 108). I then studied in a similar way the 

 optic nerve. The fibres in this nerve were smaller than those from 

 the other nerves which I had macerated, but they were much larger 

 than those figured by Patten. Each fibre (Pig. 36) possessed a distinct 

 sheath, and its contents were marked by lines which extended parallel 

 to its long axis. These lines I interpreted as indications of fibrillse 

 which composed the fibre. In addition to the large fibres, the optic 

 nerve, as well as the other nerves, showed, when macerated, the fibrous 

 shreds which I have previously mentioned. They were very insignifi- 

 cant in amount, forming, I should judge, not more than a fraction of one 

 per cent of the whole optic nerve, and I was never able to trace them 

 as continuous fibres for any considerable distance. I believe that here, 

 as in the retina, they arose from an artificial tearing of the tissue. 



At about this time I happened to find the modification of Weigert's 

 method of straining nerve-fibres, which I have described in the Intro- 

 duction. As soon as I was aware of the results which could be obtained 

 by this method, I applied it to a series of transverse sections of the 

 optic nerve. The series extended from the retina to the optic ganglion, 

 and demonstrated conclusively, I think, that the proximal ends of the 

 seven proximal retinuhe, after passing through the basement membrane, 

 as I have described, continued inward as fibres, and finally passed into 

 the substance of the optic ganglion. Figures 21, 22, 23, 24, and 25 

 illustrate steps in the passage from the retina to the ganglion. In Fig- 

 ure 21 the groups of three or four proximal retinula? are seen as they pass 

 through the basement membrane. Figure 22 is taken at a level imme- 



