PaptllcB atid Nerves of the Tongue of the Frog. 285 



arises from two branches which converge near the papilla as 

 if they were afferent and efferent. It will be preferable that the 

 blood should be found circulating in the papilla, in order to 

 detect more readily the papillary nerve. In cases where the 

 animal has been killed by strychnia, I have always found these 

 nerves more easily distinguishable, as if this substance exerted 

 some effect on the constitution of the nervous system. 



I considered it important to determine whether any vesicular 

 matter existed in the papilla, such as has been described to 

 exist at the extremities of some of the nerves of sensation. In 

 one or two instances I have distinguished some granular matter, 

 but in most cases I have not been able, whether from its non- 

 existence or from its being hidden by the engorged vascular 

 coil, to detect the slightest trace of it. 



Besides these nerves of the fungiform papillae, there exist 

 others which are spread over the lower surface of the tongue. 

 They consist of nearly simple nervous fibres, forming a kind 

 of network under the mucous membrane. This nervous net- 

 work corresponds to the capillary network distributed to the 

 mucous membrane, in the same manner as the nervous papil- 

 lary coil corresponds to the vascular one. During winter the 

 epithelium of the frog's tongue becomes thinner and more 

 transparent, and the animal is also in an anaemic condition, 

 from which causes the vessels of the tongue are but very slowly 

 engorged ; these cases are therefore the most suitable for the 

 inspection of the nerves. 



Tongue of the Toad. — The toad's tongue presents very close 

 analogies to that of the frog. I have already described in this 

 journal the slight differences which distinguish them from 

 each other. I shall now merely state what a further investiga- 

 tion has shown me with respect to their nervous structure and 

 papillae. The difficulty of procuring these animals in the 

 winter has prevented my thorough examination of the distribu- 

 tion of the nervous trunks of their central parts, but as far as 

 I have examined I find a similar distribution to those in the 

 frog. The toad's tongue is less extensible and more thick 

 than that of the frog, and for that reason it is necessary to 

 select a very small animal for microscopic examination. The 

 nervous trunks which ramify in the muscles and accompany 

 the vessels appear to be more numerous than in the frog. The 

 muscular striae are more distinct, and the fibres are arranged 

 more like separate muscles. The papillae conicic, or rather 

 tliose that correspond to them, may be compared in general to 

 irregular folds or plaits of the intestines; others are like small 

 cylindrical villi; while some fewer are convex elevations, with 

 a very small dark circular foramen in the centre and a passage 

 leading perpendicularly withui them. 



