MUSEUM OF COMPARATIVE ZOOLOGY. 27 



examination of these sections, I was entirely unsuccessful in discovering 

 any trace of nerve-fibres such as Patten had described. I therefore 

 resolved to try his methods of maceration. This I did, following closely 

 his directions as to the strength of solutions, length of time during 

 which reagents should be employed, etc., but my results were again 

 negative. Still adhering to the reagents which he had recommended, 

 especially chromic and sulphuric acids, I varied the time during which 

 the eyes were treated, hoping thereby to obtain a combination more 

 favorable for Horaarus. The separation of the elements of the retina 

 was often very successful, but I never saw in any of my preparations 

 systems of nerve-fibres which resembled those figured by Patten. In 

 almost all cases the isolated parts of the retina presented many delicate 

 fibrous projections. These projections might be interpreted as shreds 

 of broken nerve-fibres, although in no case did they show a systematic 

 arrangement. Moreover, they were found on all kinds of tissue. For 

 these two reasons, I believe that they were not broken nerve-fibres, but 

 simply shreds of tissue. The substance of the cones was finely granular, 

 and was never penetrated, so far as I could discover, by any fibres. My 

 results from both sections and isolation preparations were invariably 

 negative ; and as my observations had been made upon somewhat over 

 sixty lobsters' eyes, I concluded that in Homarus there was no evidence 

 in favor of the method of nerve-termination which Patten had described. 

 As I have previously mentioned, it is highly improbable that the 

 methods of innervation in the retinas of Penseus and Homarus are fun- 

 damentally different, and since I have found in the retina of Homarus 

 no confirmation of Patten's views, I am of opinion that he must be mis- 

 taken as to the method of nerve-termination in Penaeus. Many of 

 Patten's figures of the individual nerve-fibres in Penseus ('86, Plate 31, 

 Figs. 69, 70, 71) resemble so closely the fibres which I have seen in all 

 of my isolation preparations, and which, for reasons already given, I am 

 persuaded are not nervous, that I am forced to believe that Patten has 

 mistaken for nerve-fibres shreds of non-nervous tissue. 



My criticism of Patten's results refers only to those which he obtained 

 from a study of the Crustacea. No one, so far as I am aware, has fully 

 confirmed his views concerning the nerve-terminations in this group. 

 Kingsley ('86, p. 864) claims to have seen the axial nerve-fibre in 

 Crangon, but he was unable to trace its finer ramifications in the cone. 

 He states ('87, p. 57), however, that the method of preparation which 

 he employed was not intended especially for the fibres, and that there- 

 fore it is not surprising that they were not identifiable. Herrick 



