ANIMAL NATURE OF DIATOMEiE. 359 



complicated than what was formerly ascribed to these, 

 they may, on the other, claim to represent the ordinary 

 conditions of the elementary cell. 



Ehrenberg has described and delineated in many so- 

 called Polygastric Infusoria, a mouth and anus, many 

 vesicular stomachs, secerning glands representing the 

 masculine sex, and ovaries along with these, together 

 with one or more eyes in very many. The existence of 

 such organs, in certain species, seems to be a fact now 

 placed beyond controversy and beyond doubt. But the 

 criterion by which the organs themselves are judged by 

 analogy to exist in other microscopic beings, are not 

 equally certain. Thus in the Closteria, and generally in 

 all the Desmidiese, it is clear that Ehrenberg is egregiously 

 mistaken. 



He supposed to be a stomach the nucleus, which, in 

 Closteria, as in Zygnemata, is, from the first, suspended 

 in the middle of the cell, and is large, transparent and 

 colourless : but in order that these might systematically 

 be termed Polygastric Infusoria, he applied the names 

 of stomach and spermatic glands promiscuously to grains 

 of starch and gonidia in their different states of develop- 

 ment. Chlorophyll and all the rest of their contents he 

 arbitrarily represented as ovaries. 



The introduction of a coloured substance, accomplished 

 only once in a Closterium, and only into one of the 

 vesicles situated at the two extremities, proves no more 

 than this, that the supposed terminal apertures may 

 really be found in certain species at certain periods of 

 their existence. And we know that in vegetable cells, 

 at certain periods, there are formed in certain parts of the 

 plant, circumscribed and regular apertures through 

 which the contents issue forth. The mere presence of 

 an aperture, and the introduction of exterior solid sub- 

 stances through this opening, cannot, therefore, be an 

 absolute character of animality ; for this, like other cha- 

 racters, is only of value as it is in accordance with the 



