Ill 



oloured substance of these animalcules, which, sur- 

 ounded with the coat, colours them in a particular 

 manner. These substances appear to me in general 

 gelatinous, half liquid, homogeneous, containing drops 

 f oil or of fat, and very small solid grains. 



In the Surirella Venus, this substance forms a 

 jrown or green mass (fig. 4. e.) , heaped in the 

 middle of the animalcule. In the Naviculae , the 

 Trastuliae, and in some of the Diatomeae, this mass 

 'orms a small thin leaf, coloured, bent in its edges 

 downwards, such as in the Frustidia appendiculata, 

 PI. I. fig. 13. c. c. ) which, when the animalcule 

 dies, is irregularly dissolved. The genus Scalplrum 

 uid some species of non- described Naviculae, can 

 jxpell, without dying, the coloured content, through 

 ;he opening found on the surface of the belly (PI. V. 

 fig. 70. b.) and these animalcules seem to possess the 

 faculty of reproducing the content. 



This content is equally seen in the Diatomeae and 

 Fragilariae, and the two extremities of the body alone, 

 being empty , are transparent. In the articulations 

 of the Diatoma fenestratum, it merely consits in pale 

 globules, always single and of various size (fig. 38.). 



The genus Closterium, and those which are related 

 to it, are on each side filled with a green substance, 

 similar, though chemically different, to the chloro- 

 phylle of leaves : which substance covers large drops 

 of a yellow oil (fig. 57. h. fig. 64. f. ). This sub- 

 stance is here, as well as in the Frustuliae, intercepted 

 in the middle of the body , and consequently divided 



