THE NERVOUS SYSTEM. 425 



"fibres of Remak," I do not look upon in the common sense as a root, 

 but as a branch, arising from the superior cervical ganglion, and pro- 

 bably the other cervical ganglia ; as well as the rami communicantes, 

 seeing that individual fibres of them, actually join peripherally the 

 spinal nerves ; and the rami cardiaci, pulmonales, &c. Other branches 

 in the parenchyma of the organs become so fine, that it is impossible to 

 trace them. What has been as yet established respecting their ultimate 

 course, is as follows : 1. Divisions occur in the branches and terminal 

 ramifications of the sympathetic, as in the nerves of the spleen, the 

 Pacinian bodies in the mesentery, in the nerves accompanying the 

 mesenteric vessels in the Frog, in those which exist temporarily in the 

 uterus of the Rodentia, of the lungs and stomach of the Frog and 

 Rabbit, of the dura mater on the meningeal arteries, in branches of the 

 sympathetic of the Sturgeon, in the cardiac nerves of the Amphibia, 

 and in those of the urinary bladder in the Rabbit and Mouse. 2. There 

 are free terminations of the nerves, as in the Pacinian bodies and on the 

 mesenteric vessels in the Frog. 3. The thicker fibres of the sympathetic 

 ultimately so decrease in size as to become of the fine kind; as may be 

 readily seen in the rami intestinales, lineales, and hepatici, which, indeed, 

 even in the interior of the organs in question, contain some coarser 

 nerve-fibres, but ultimately lose them. The actual terminations, how- 

 ever, in the organs themselves, in the heart, lungs, stomach, intestine, 

 kidneys, spleen, liver, uterus, &c., are as yet quite unknown ; although 

 from the impossibility of finding any dark-bordered fibres in the ultimate 

 ramifications of these nerves, it may be supposed that they terminate, 

 almost everywhere, in non-rnedullated, embryonic fibres. In fact, I 

 have, at all events hitherto, in vain endeavored to find a trace of them. 

 Schaffner says, that in the heart of Bombinator he has seen the passage 

 of the dark-bordered fibres into pale, anastomosing fibrils of the finest 

 kind, whilst Pappenheim (1. c.) describes loops in the nerves of the 

 kidney. 



As regards the nature of the "fibres of Remak," most recent ob- 

 servers incline to the opinion first advanced by Valentin (" Repert.," 

 1838, p. 72; Muller's "Archiv," 1839, p. 107), that they are not nerve- 

 fibres at all, but to be referred to the connective tissue of the nerves ; 

 whilst Remak still thinks himself obliged to adhere to his previous 

 opinion, that they are, or may be, in part at least, nerve-fibres ("Darm. 

 nervensyst.," p. 30). As for myself, I freely acknowledge the force of 

 the reasons adduced by the latter observer, which are based chiefly upon 

 the similarity of the fibres in question to the pale embryonic nerve- 

 fibres, inasmuch as that even in the adult, nucleated nerve-fibres are met 

 with in the olfactory nerve ; but I am compelled, nevertheless, as before, 

 fully to concur with Valentin, as do also Bidder and Volkmann, and 



