NATURE'S JEWELS. 169 



generally in the Diaiomacece., is somewhat of a 

 puzzle, and in this connection one is apt to ask 

 whether the beings we are observing are of animal 

 or vegetable nature ? Here there is considerable 

 diversity of opinion among the authorities, for 

 while some think that their animality is beyond 

 a doubt, others, and these the majority, are certain 

 that they belong to the vegetable kingdom ; the 

 truth probably being that they belong to both, but 

 are not absolutely one or the other. It is time 

 that naturalists recognised in popular descriptions 

 the fact, of which they are so well aware, that the 

 phrase " animal and vegetable kingdoms " is not 

 of divine authority, but purely of human invention. 

 It is well known now that there is no sharp divid- 

 ing line between animal and vegetable, where the 

 one ends and the other begins ; but that on the con- 

 trary, on this border-lan,d the two blend into each 

 other plant-animal and animal-plant, being well 

 recognised in numerous instances, of which also the 

 Diatom is probably one. The various keen dis- 

 putes, however, have not been altogether fruitless, 

 for both parties, in order to sustain their own 

 special view, have probably brought closer obser- 



