370 ANIMAL NATURE OV DIATOME^. 



the form of phycoma. In some species of Schizonema 

 and Micromega, he found contained within the same 

 substance, globular bodies, which he saw successively 

 enveloped in new phycoma, whilst the included sub- 

 stance, at first minutely granular, grew into so many 

 Naviculse. The observation is valuable, and furnishes a 

 very important subject for study. For, whilst in other 

 cases the difficulty of keeping pace with the successive 

 development of the same individual obliges us to observe 

 comparatively, different individuals, in respect of which 

 there may always exist a doubt whether they really 

 belong to the same species, here we have, as it were, 

 a whole brood, consisting of individuals which pre- 

 sent, at the same time, all the phases of their de- 

 velopment. And this expression of (covey or) brood 

 is not here used at random ; since no direct argument 

 beyond that from external resemblance, tends to show 

 that these reproductive bodies are true spores; whilst, 

 in the animal kingdom we find equally numerous analo- 

 gies, as well in the ovaries of Polyps and other inferior 

 animals, as in many Ovipara of superior classes. And in 

 fact the bag of a spider, with the thousands of small eggs 

 that it contains, seems to me quite as like as the spore 

 of an Alga to the organ of propagation of a Schizonema 

 or a Micromega. 



Finally, in respect to the movements of Diatomese, 

 Kiitzing's opinion evidently accords with ours ; since, 

 after treating at some length on the question of their 

 animal or vegetable nature, he arrives at the singular 

 conclusion that Diatomese consist of three substances : 

 1, one inorganic, constituting the shield; 2, one 

 organic and vegetable, constituting the internal gonimic 

 substance, the external envelope, and the peduncles ; 

 3, one organic and animal, from which are formed the 

 organs of motion. We cannot admit this third opinion, 

 inasmuch as he assigns organs of motion even to the 

 lower vegetables and their spores, similar to those which, 

 according to him, partake of something like animal life. 



