482 SPECIAL HISTOLOGY. 



having exactly the same characters as those of the so-termed 

 sympathetic exist in many other situations, as for instance, — in 

 Man and the Mammalia, — in the posterior roots of the spinal 

 nerves and of the sensitive cerebral nerves, in which situations, 

 as I have already shown, there can be no question whatever as 

 to a derivation of the fibres from the sympathetic, and where 

 we have, presented to us, nothing but fine cerebro-spinal fibres ; 

 similar fibres are contained by thousands in the spinal cord and 

 brain, as well as in the two higher nerves of sense. 3. All 

 thick nerve-fibres decrease in size in their ultimate ramifications, 

 owing to divisions, or direct diminution, so that ultimately they 

 acquire the diameter and nature of the fine, and finest kinds of 

 fibres. 4. All thick nerve-fibres in the course of their develop- 

 ment are, at one time, exactly in the condition of the so-termed 

 sympathetic fibres. From these facts it would appear certainly 

 evident, that it is impossible to regard the fine fibres of the 

 sympathetic as altogether of a special nature, and peculiar to it 

 alone, and that it will not do, in the anatomical point of view, 

 to classify the fibres according to their size, very many in fact, 

 in their course, assuming all possible degrees of thickness. 

 Allowing that the great number of very fine pale fibres in the 

 sympathetic is a prominent anatomical fact, as is also indeed 

 the case in the higher nerves of sense and in the grey substance, 

 still, speaking physiologically, I am by no means of opinion 

 that the fineness of the fibres in the sympathetic indicates any- 

 thing of a special nature in them, and which does not exist 

 elsewhere, but perhaps, that where this condition does exist 

 both in them and in other situations, it is connected with a 

 distinct kind of function.] 



§ 125. 



Peripheral distribution of the ganglionic Nerves. — From the 

 main trunk of the sympathetic arise the branches proceeding 

 to the periphery, which, without exception, receive finer and 

 thick fibres from it, but besides these, in part at least, contain 

 other special elements, to which is due their varied aspect. 

 Some of them, for instance, are white, as is the main trunk in 

 most situations, such are the n. splanchnici ; others greyish 

 white, as the nervi intestinales, the nerves of the unimpregnated 

 uterus (Remak, ' Darmnerven System/ p. 30); others again 



