Bacillaria.] THE INFUSORIA. 183 



ing material was really existing internally ; but if a glass 

 plate is placed upon it, and then properly removed, the 

 globule of colouring matter may be taken away. The 

 unprejudiced reader must then see that much observation 

 is yet wanting ere we can hope satisfactorily to determine 

 that the Bacillaria are truly animals; and how closely 

 plants and animals border upon each other is recognizable 

 in the spermatic animalcules of the lower plants, and the 

 spermatic animalcules of animals/ 5 



SECTION I. DESMIDIACEA. 



Genus XLIV. DESMIDIUM. The chain-wanded Animal- 

 cules. The lorica is of a simple triangular box-like form, 

 with a single aperture in the centre ; in texture it resem- 

 bles parchment. The animalcules possess the power of 

 slowly transporting themselves from one place to another, 

 but no organ of locomotion has been detected. Green 

 ova-like granules are observable in all the species, and 

 among them in D. Swartzii, orbiculare, and aculeatum, 

 colourless vesicles, probably digestive cells. It is doubt- 

 ful, says Dr. Ehrenberg, whether they are developed singly 

 or in pairs. 



161. DESMIDIUM Swartzii. Swartz's Desmidium has 

 a triangular lorica, which, when viewed edgeways, appears 

 quadrangular. They are attached together, forming a 

 chain-like body, of a green colour. Diameter of a single 

 animalcule l-2300th to 1-1 100th. Found amongst 

 conferva. 



162. DESMIDIUM orbicular 'e. The disciform Desmidium 



