LIFE AND ORGANISATION. 65 



higher animals, even the highest, which breathe air on tho 

 surface of the globe. 



Another result of recent enquiry has been our increased 

 knowledge of the Entozoa, and of Parasitic life generally, both 

 animal and vegetable in kind. No natural phenomena are 

 more curious than these. A few examples, seemingly rather 

 deviations from nature than a part of it, formerly comprised 

 all we knew on the subject. Now we may fitly term it a 

 branch of natural history in itself, so numerous are the 

 instances, so definite the relations it involves. When we find 

 even the earth-worm haunted by a parasite (the Gregarina) 

 living within and upon it ; and numerous mollusks and insects, 

 with peculiar entozoa pertaining to each, we gain some idea 

 of the extent and singularity of these relations. It is not an 

 anomaly we look upon, but a part of creative intent ; an 

 expression of that great design which makes organised life 

 in one form everywhere subserve to the maintenance of 

 another. Exception may perhaps be taken for those species 

 of parasites which are found in diseased animal textures, and 

 in such alone ; as we recognise them in morbid states of 

 which man himself is the subject. These curious cases have 

 been considered to sanction the hypothesis of equivocal 

 generation, of which we shall speak hereafter the disease 

 itself being regarded as antecedent, and the parasitic life as 

 growing out of it. It would be difficult to bring positive 

 proof on this point. It is one reserved for future research ; 

 as are those strange analogous phenomena which seem to 

 show that the same ova or parasitic germs, transferred to 

 different organic textures, are capable of evolving different 

 forms of animal life. Minute though these objects be, and 

 inaccessible to all unaided sense, there is no part of natural 

 history which strikes deeper roots into the secrets of the 

 living creation. 



Eising higher in the scale of existence, we find in all the 



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