COMMON MOUSE. 67 



the number of 120, all which, he concluded, were 

 the descendants of the mouse he had inclosed. 



The fur of the Mouse is remarkably soft and 

 elegant, and the structure of the hair in this ani- 

 mal, as well as in the rat, and probably of many 

 others of this genus, is singularly curious ; each 

 hair, when microscopically examined, appearing 

 internally divided into a kind of transverse par- 

 titions, as if by the Continuation of a spiral fibre ; 

 a structure very diiferent from that of the hair of 

 most other animals, and of Mdiich the particular 

 nature seems not very distinctly understood. 



Derham, in his Physico-Theology, conceives 

 that this mechanism of a spiral fibre may serve 

 for the gentle evacuation of some humour out 

 of the body," and adds, that ''perhaps the hair 

 serves as well for the insensible perspiration of 

 hairy animals as to fence against cold and wet." 

 Whatever be the real nature or use of the above 

 structure, its appearance cannot fail to excite 

 astonishment in those who take the pains of exa- 

 mining it with a good microscope. In the an- 

 nexed plate are introduced some figures of the 

 hairs of a Mouse, highly magnified, in order to 

 give a clear idea of this curious appearance. 



In Aldrovandus, who relates the circumstance 

 from Gesner, we meet with a direction for chang- 

 ing, as it were, a mouse into a cat, by making it 

 the incessant persecutor and enemy of the rest of 

 its species. This is to be effected by placing 

 several mice together in a vessel, without food ; 

 when, after a certain space, they will be so stimu- 



