the Origin of hitestinal TTorms. 353 



lupinosa)y and found them to consist of cryptogamous plants. 

 I have made a similar observation respecting the Aphthoi of 

 children, though, at the same time, I must confess that I am not 

 so conversant with the microscopical structure of plants, com- 

 pared with that of pathological formations, as to consider my- 

 self an authority on the point. To suppose aphthae contagi- 

 ous, would undoubtedly be contrary to the prevailing opinion, 

 though several facts induce me to suspect them to be so. In 

 Greenland this disease is not known. In a family of my ac- 

 quaintance which lived there for many years, none of the chil- 

 dren born during their residence in the country suffered from 

 it, whereas all those born after the family returned to Co- 

 penhagen suffered from it as do most other new-bom chil- 

 dren in that city. This may be ascribed to a difference of 

 climate, but in the Greenland houses a high temperature is 

 maintained ; or to a difference of diet, but the Danish families 

 in Greenland live upon provisions sent from Denmark, with 

 a few slight differences, such as that of eating the flesh of the 

 reindeer for that of oxen. 



CHAP. VI. CONCLUSION. 



Sect. 1. General Bemarks upon Parasitical Life, — After 

 what has been said in the foregoing chapter, it might be re- 

 garded as established, 1. That parasitic life exists everywhere 

 around and within other organisms. The soil is adapted to 

 plants, plants for the use of animals, and animals (although 

 wholly appropriated to their individual use) appear to be sub- 

 jected to the use of parasites. As examples, we might adduce 

 any one of those instanced in the foregoing pages concern- 

 ing intestinal worms ; I shall, however, take an illustration of 

 my remark from a different class of parasite animals. The 

 univalvular molluscum adapts the form of its shell to its own 

 use, but this form is at the same time precisely adapted to the 

 use of a pagurus, whose whole body is twisted like this shell ; 

 whose claws exactly fill up its opening ; whose tail is naked 

 and provided with very minute limbs, enabling it to creep 

 within the shell, and nowhere else. 2. That parasitic life, 

 though wholly dependent upon other animals for support, ori- 

 ginates and is propagated in conforjnity with tjie same gen^yal 



