WORMS 307 



of a cartilaginous texture, which rise to a sharp crescentic 

 edge; they form a triangular, or rather a triradiate, figure. 



Now, if you recollect, this is the figure of the cut made 

 in the flesh wherever a Leech has sucked, as it is of the 

 scar which remains after the wound has healed. For these 

 three little eminences are the implements with which the 

 animal, impelled by its blood-sucking instincts, effects its 

 purpose. But to understand the action more perfectly, 

 we must use higher powers. 



I dissect out of the flesh, then, one of the white points, 

 say the middle one, and laying it in water in the compres- 

 sorium, flatten the drop, but use no more pressure than 

 just enough for that. Now I apply a power of 150 diam- 

 eters, and we will look at it in succession. You have 

 under your eye a sub-pellucid mass, of an irregular oval 

 figure, and of fibrous texture, one side of which is thinned 

 away apparently to a keen edge of a somewhat semicircular 

 outline. But along this edge, and as it were imbedded 

 into it for about one-third of their length, are set between 

 seventy and eighty crystalline points, of highly refractive 

 substance, resembling glass. These points gradually de- 

 crease in size toward one end of the series, and at length 

 cease, leaving a portion of the cutting edge toothless. At 

 the end where they are largest, they are nearly close 

 together, but at length are separated by spaces equal to 

 their own thickness. The manner in which they are in- 

 serted closely resembles, in this aspect, the implantation 

 of the teeth in the jaw of a dolphin or crocodile. 



But this appearance is illusory. By affixing the little 

 jaw to the revolving needle, we bring the edge to face our 

 eye. It is not an edge at all; but a narrow parallel-sided 

 margin of considerable breadth. And the teeth are not 



