112 



into two equal parts. In the Closterium Lunula (fig. 

 57.) , it is partly separated by sharp teeth 5 in other 

 species, sucli as the Closterium spiral e (fig. Q7. h. ), 

 it appears like a green spiral ribbond in the cavity 

 of the coat. 



In the Pediastra , Euastra, Stauridia , Cosmaria 

 and in the Colpopella, the green substance fills entirely 

 the two articulated parts of the animalcule, and hides 

 often from one to four drops of oil (fig. 30. 31. 35. 

 a. a.) 5 but, near these drops, small solid and dark 

 grains (b. b.) are seen swimming, and in a continual 

 oscillatory motion , like the corpuscules of the rota- 

 tory vesicle of the Closteria. The same takes place 

 in the Scenodesmi, Echinellae , Sphaerodesmi, etc. 



In the Oscillatoriae the content consists in small 

 disks, placed close one another, having only a small 

 cavity, for ex. in the Oscillatoria labyrinthiformis 

 (PI. VI. fig. 76. a.). 



ORGANS OF PROPAGATION. 



The organs of generation are in this series very 

 obscure and problematic. I do not know them. I 

 shall however hazard a few observations , perhaps 

 of some importance , which may he brought under 

 this head, as long at least as we shall not be able 

 to point out these organs more positively. 



