cxxii Journal of Comparative Neurology. 



so as to agitate the nerve trunk as well as the skin, will produce numb- 

 ness.] 



Subsequently the author found in the tuning rhetome an available 

 means of applying intermittent electrical stimuli. 



Anaesthetic effects were produced by 540 vibrations (C major) but if 

 the vibrations ascended above D axacerbation of the pain resulted. The 

 practical application to minor surgical operations and neuralgia seems 

 valuable. 



[The reason why the more rapid notes fail of anaesthetic effect, may be 

 that the wave length of nervous excitement is such that more rapid excite- 

 ment causes the waves to fuse, resulting in general hyperaesthesia of the 

 fibre. Some experiments carried on by the writer's students seem to 

 show a great variability in the upper limit at which vibratory stmuli may 

 be recognized.] We are promised special apparatus for this purpose. 



Some Remarks upon the Eyes of Sah'a.i 



The eyes of salpa are situated upon the dorsal surface of the brain 

 and have been differentiated from it. In the simplest case, the eye is 

 represented by a single dorsal swelling. The major portion of the swell- 

 ing is composed of the retina, the elongated cells of which constitute the 

 whole of th6 dorsal surface of the eye. These cells occupy a single row, 

 and their longitudinal axes are perpendicular to the surface of the eye. 

 At the base of this swelling there is a girdle of pigment cells. Both the 

 pigment cells and the retinal cells have been derived from the ganglion. 

 Here, as in all Salpidae, the retina contains two kinds of tells, "sehzel" 

 len " and " stutzzellen." The " stutzzellen " form a sort of framework 

 in which the " sehzellen " are imbedded. During life the "stutzzellen" 

 are, probably, pigmented. In this simple case the retina cells are situ- 

 ated between the nerve fibres and the surface. 



The change that has taken place in more complex eyes can be best 

 understood by a study of the horse-shoe shaped eyes. The central por- 

 tion of such an eye consists of a simple dome-shaped eye similar to the 

 one just described ; but the lateral arms are quite different. At we pass 

 towards the extremity of such an arm, we find that the retinal cells have 

 rotated more and more latero-ectad until, finally, they are perpendicular 

 to their original position. During this rotation the nerve-fibres have 



1. BlfBTSCHLi, O. Einige Remerkungeii ueber die Augen dor Salpen. ZooL An- 

 zeiger, XV, Jahrg, s. :i4!). 



