LANCETS AND THEIR SHEATHS. 



83 



sheath between the toes, when it is not in use. This sheath 

 is exactly the same in principle as that of the Indian tulwar, 

 and any one can examine it by looking at the foot of a good- 

 tempered cat. I have done so even with a chetah, which is 

 not a subject that would generally be chosen for such a 

 purpose. 



On the next illustration is shown an ordinary Lancet, in 

 which the blade is guarded between a double sheath, the two 

 halves and the blade itself working upon a common pivot. 

 As for the drdinary sword and dagger sheaths, it is not worth 

 while to figure them. 



Turning to the opposite side of the illustration, we shall see 

 a few of the innumerable examples in which the principle of 

 the sheath was carried out in Nature long before man came on 

 the earth. 



The reader should compare this figure with the side view of 

 the Gnat's lancets given on p. 81. 



They represent the cutting and piercing instruments of 

 several insects, all of which are very complicated, and are 



surgeon's lancet 

 partly open. 



LANCETS OF TABANUS 

 CLOSED. 



LANCETS OF MOSQUITO 

 PARTLY OPEN. 



sheathed after the manner of the lancet. Indeed, they are 

 popularly known as "mouth-lancets," and with reason, as 

 the reader may see by reference to the illustration. 



g2 



