CUTANEOUS NERVE-TERMINATIONS IN MAMMAIS. 589 



recalling the drawiugs of Dr. Lionel Beale of such nerves and 

 blood-vessels, with which, indeed, they are identical. 



In the Hedgehog, on the contrary, from which fig. 27 was 

 drawn, tliere is no such regular superficial plexus of blood- 

 vessels ; and the spaces between the groups of hair on the belly 

 being perfectly flat and transparent, we have the appearauce 

 presented in fig. 28, where the irregularity o£ the nerve-plexus 

 seems absolutely unaffected by the irregular character of the 

 blood-vessels. The irregularity there resembles somewhat the 

 plexus as it exists in the larger Mammals, which, however, is 

 generally seen only in perpendicular sections showing the side 

 views of the fibrils. 



The number of cells forming the groups also varies much in 

 difi"erent auimals. In Man they are very few; in the Pig they 

 are plentiful. Fig. 22, Plate XVI., gives a drawing of one of the 

 large groups we have found on the lower surface of the epidermic 

 downgrowths of the snout of that animal, as seen from our point 

 of view and preparation, and drawn by the aid of the camera lucida. 

 It will appear to differ considerably from the drawings published 

 by Merkel, Bonnet, and Eanvier. We have omitted altogether 

 the epidermic cells from the drawing, below which the group of 

 nerve-cells lay, as they would only serve to obscure it. In that 

 group a medullated nerve joins the plexus, breaking up into two 

 branches before doing so ; but alongside of the medullated nerve 

 were several non-medullated fibres, which equally passed to join 

 the plexus, and from the plexus branches were given off laterally 

 to join other portions of the subepidermic plexus. Tlie difference 

 in the size of the cells in different animals may be noticed by com- 

 paring this figure with figs. 19 & 21 (from the Horse) and fig. 23 

 (from the Bullock), all of which were drawn under the same lens 

 and magni£ying-power. All these ganglia or groups of cells 

 belong, in our opinion, to the sympathetic system of nerves ; and 

 we may mention also, with reference to the medullated nerves 

 which join them, that in some animals, such as the Horse, it is 

 excessively rare to find a medullated nerve joining or apparently 

 having even an indirect connexion with a grouj), although several 

 non-medullated nerves may be seen passing to it from the deeper 

 part of the dermis. 



We are inclined to look upon these groups as peripheral nerve- 

 centres, within the cells of which are generated the currents which 

 convey the sensation of paiu or other influences either to the 



