BEGINNING OF NERVES. 



307 



logical work. But, as the physiology of the subject continued to open 

 up in the wonderful way in which it did, I felt it was undesirable either, 

 on the one hand, to suspend this part of the inquiry, or, on the other 

 hand, any longer to defer a thorough investigation of the histological 

 part. I therefore represented the case to my friend Mr. Schafer, who 

 very kindly consented to join me in Scotlandj with the view of cooper- 

 ating with me in the research. The histological results wdiich he has 

 obtained from a most skillful and painstaking investigation are in the 

 highest degree interesting. He worked chiefly with Aurelia aurita^ 

 and found that the tissue which performs the ganglionic function in 

 the marginal bodies is of the nature of modified epithelium-cells, the 

 ganglionic function of which could scarcely have been suspected but 

 for the paralyzing effects which are produced by their excision. From 

 these marginal ganglia there radiate what he regards as delicate pale 

 nerve-fibres, which sometimes present the appearance of fibrillation. 

 These fibres spread over the entire expanse of the muscular sheet in 

 great numbers. It will thus be 

 seen that these microscopical 

 researches of Mr. Schafer fully 

 bear out my inference from the 

 result of physiological exper- 

 iments, which was previously 

 published at the Royal Society 

 — the inference, namely, that 

 the entire muscular sheet of 

 the 3fedusce is overspread by 

 a dense plexus of nervous chan- 

 nels. But these researches of 

 Mr. Schafer tend to negative 

 another inference which was 

 published at the Royal Insti- 

 tution — the inference, namely, 

 as to the degree in which these 

 channels are differentiated.^ As the facts on which this inference was 

 based have not been previously published in the Fortnightly Review., 

 and as, apart from the dubious inference, they are facts of the first im- 

 portance, it is necessary that I should here very briefly restate them. 

 The annexed woodcut (Fig. 3) represents a specimen of Aurelia aurita 

 with its polypite cut off at the base, and the under or concave sur- 

 face of the bell exposed to view. The bell, when fully expanded, 

 as here represented, is about the size of a soup-plate, and in it all 



' I may here state that, previous to Mr. Schiifer's researches, I had observed both 

 the tissue-elements which he describes ; but I hesitated to pronounce upon their nervous 

 character. It will thus be understood that even now, without wishing to dispute the 

 accuracy of his judgment in this matter, I do wish it to be known that the responsibility 

 of this judgment rests entirely with my friend. 



Fig. -2. 



