ANIMAL NATURE OF DIATOMEjE. 347 



to impressions already received and to those which may 

 be received hereafter. These ideas are hence more or 

 less incomplete in every observer, nay, incomplete in all, 

 because no one has seen every animal or every plant. On 

 this account we not unfrequently meet with organisms of 

 an ambiguous nature, which at first sight appear equally 

 to belong to the animal and the vegetable kingdom. But 

 yet with regard to this ultimate division of organic 

 beings, we ought to proceed in the selfsame path which 

 we find necessary to follow in respect to the first divisions 

 of Species and Genera. When a naturalist meets with a 

 species that appears to belong to two different genera, 

 and to form a transition, so to speak, between one and the 

 other, he decides according to the importance and the 

 value of the characters, either to modify the definitions 

 of the two genera, or to propose a new one, or to fuse 

 both together into one. He would sin against Ontology 

 should he assert that he found the two genera included 

 and combined in the ambiguous species. The genus has 

 existence only in our minds, and not in the species. In 

 the latter we can only discover some or all the charac- 

 teristics of the genus ; that is, certain signs which con- 

 stantly subsist in every sister species, whatever may be 

 their diversity in other respects. Thus Kiitzing, when 

 he says that in the Diatomese the two elements, the 

 animal and the vegetable, are combined and in equilibrio 

 with each other, gratuitously imagines the idea of a com- 

 bination, which in reality can only take place between 

 difierent substances, and hence he applies his conjecture 

 to the expression, instead of applying the latter to the 

 former. And he draws his conclusion from the example 

 he uses, instituting this same comparison between the 

 organic and inorganic kingdom, and deducing from it 

 analogous consequences ; the gradual transition from one 

 to the other is as it were their conjunction, through 

 the same intermediate ring or circle of Diatomeae. 



The phosphate of lime, he says, which constitutes so 

 large a portion of the bones of animals, the silica of 



