ANIMAL NATURE OF DIATOME^. 367 



cessive alteration in them, as if these minute globules 

 mixed themselves with larger ones, and separated again 

 from them. 



Finally, with reference to the supposed stomachs of 

 Ehrenberg, hitherto no fact enables me to satisfy myself. 

 I will only remark that, exactly in the median region of 

 Naviculfs, corresponding to the large aperture, the mem- 

 branous production before mentioned may be seen ex- 

 tended across, during life; and this, vanishing after 

 death, leaves in its stead an ample transparent area, of 

 circular figure, and surrounded by those granules that 

 take colour with indigo. 



We will now continue the analysis of Kiitzing's 

 anatomical and physiological observations. All the 

 Diatomeas, he says, give out through their apertures a 

 mucous substance, which he calls jelly, to identify it 

 with the vegetable jelly; this either diffuses itself in 

 water, or collects into various shapes, or contains entire 

 and determinate simple or multiple series of Naviculae, 

 forming one or more gelatinous tubes, which, detached 

 or connected into bands, assume the form of the Phycoma 

 of true Alga3. I confess that I have no arguments to 

 controvert the foregoing indication of the origin and 

 formation of the peduncles in Achnanthea?, Gompho- 

 nemea3, and Ulnarire ; but to any one who has observed 

 these beings, the explanation will not be satisfactory at 

 all. It would be more probable to suppose that this 

 peduncle should represent the original cell within which 

 the siliceous frustules were successively developed. We. 

 might again make this supposition in respect to the 

 gelatinous tubes containing the Navicula? of Schizonema, 

 Micromega, and other allied genera. But be it a simple 

 product of secretion, or of itself an organic portion, this 

 substance may equally belong to an animal and to a 

 vegetable. Kiitzing declares it to be a gelatinous sub- 

 stance, or isomeric with starch ; but adduces no experi- 

 ment to prove it. The trials I have made seem to indi- 

 cate a ternary non-azotised composition ; for when burned, 



