108 PARTICULAR CONSIDERATIONS ON THE 



digestion, and their transmission through a living body, for 

 immediate assimilation with it, or flakes of lymph detached 

 from surfaces already organized, seem neither to exceed nor 

 fall below that simplicity of structure which favours this won- 

 derful development ; and the supposition that, like morsels of 

 a planaria, they may also, when retained in contact with 

 living parts, and in other favourable circumstances, continue 

 to live and be gradually changed into creatures of analogous 

 conformation, is surely not so absurd as to be brought into 

 comparison with the Metamorphoses of Ovid. * * We 

 think the hypothesis is also supported in some degree by the 

 fact, that the origin of the entozoa is favoured by all causes 

 which tend to disturb the equality between the secerning and 

 absorbent sy stems." ( 52 ) Here particles of organized matter are 

 suggested as the germinal original of distinct and fully or- 

 ganized animals, many of which have a highly developed re- 

 productive system. How near such particles must be to the 

 inorganic form of matter may be j udged from what has been 

 said within the last few pages. 



While these appear as good general arguments for primi- 

 tive life-production as a common occurrence in nature, there 

 is a series of facts which goes a fur way to prove that such 

 occurrences must have taken place in comparatively modern 

 times. The pig, in its domestic state, is subject to the 

 attacks of a hydatid, from which the wild animal is free ; 

 hence the disease called measles in pork. The domestica- 

 tion of the pig is of course an event subsequent to the origin 

 of man ; indeed, comparatively speaking, a recent event. 

 Whence, then, the first progenitor of this hydatid ? So also 

 there is a tinea which attacks dressed wool, but never touches 

 it in its unwashed state. A particular insect disdains all food 

 but chocolate, and the larva of the oinopota cellaris lives no- 

 where but in wine and beer, all of these being articles manufac- 

 tured by man. There is likewise a fish called the pymelodes 

 cyclopum, which is only found in subterranean cavities con- 

 nected with certain specimens of the volcanic formation in 

 South America, dating from a time posterior to the arrange- 

 ments of the earth for our species. Whence the first pyme- 



