Generation of Entozoa. 



105 



they themselves are the contrivers, of the design the de- 

 signers. 



Let us then suppose that a portion either of effused lymph 

 or extravasated blood, or any other substance, is about to 

 go through the process of converting itself into an intestinal 

 worm, and consider what it has to do to effect so complete a 

 metamorphosis ; we must suppose that before it assumed its 

 independent and distinct life, the first object would be to form 

 for itself a mouth and an alimentary canal for its future sup- 

 port, a gastric juice of course, and the other necessaries for the 

 function of digestion ; now even this, in a particle of matter 

 destitute of mind or intelligence, as is the peacock's egg, would 

 seem to border a little on the miraculous. 



Well, then, having provided for what many consider the 

 most important business of life, the eating function, what has 

 it to do next ? Why to shake off the homely and ungraceful 

 form of its embryotic clot, and assume the elegant gracility 

 of an ascarid, or a Spiroptera, or the broad and jointed ampli- 

 tude of a tape-worm, the polymorphous structure of a Scolex, 

 or the inextricable complexity of a Distoma. 



Having settled this point, the clot has next to regulate its 

 growth ; clots are of very various dimensions, but the Ento- 

 zoa are as certainly defined in their limits of magnitude as any 

 other class of animals. Well, then, it must be obvious, that 

 a clot larger than the species into which it is to be converted 

 must fine itself down to the proper size, or if too small, plump 

 itself up to the same ; but by what mysterious power it can do 

 this I profess not to understand. 



Having got so far^ however, in its own creation, what has 

 it next to do ? To cover itself with a proper skin ; and in this 

 great taste is often exhibited, the integument of many worms 

 offering a very beautiful appearance; and observe the wonder- 

 ful phaenomenon connected with this. The Deity has spread 

 over the surface of animals and plants (I mean such as He is 

 acknowledged to have formed) an insensible covering, the 

 cuticle, to serve as a protection for the parts beneath. And 

 what does the clot do ? Why just the same thing ; it covers 

 itself with a cuticle too ; though indeed we need not wonder 

 much at this, after its having made for itself an alimentary 

 canal and bestowed upon it the function of digestion. 



But the work is not yet completed ; motion is not yet pro- 

 vided for, a muscular apparatus is therefore next to be fabri- 

 cated ; first, for the motion of the whole body, and next, for 

 that of individual parts ; and so perfectly is this accomplished, 

 that it often forms a source of disappointment and vexation 

 to the investigator of these animals. Some of the nematoid 



