128 SKETCH OF THE INFUSORIA 



vations enable me to confirm some of the statements and to cor- 

 rect others. 



" The author, after detaihng the histoiy of Closterium, from its dis- 

 covery by Corte in 1771, down to the present time, entered into a 

 detail of its appearance and gerleral structure ; he described it as 

 consisting of a green gelatinous and granular body, invested by a 

 highly elastic and contractile membrane, which is attached by vari- 

 able points to a hard sihceous shell, which was aftei-vvards stated by 

 ]\Ii-. C. Yarley to resist even the action of boiling nitric acid. The 

 form of Ciostcrium is spindle-shaped or crescentic — the shell con- 

 sisting of two horns, tapering off more or less to the extremities, and 

 united at the central transverse line, constituting a perfectly sym- 

 metrical exterior. At the extremity of each horn is an opening in 

 the shell, which, however, is closed witliin by the membranous en- 

 velope, wanting however in some specimens. Within the shell and 

 at the extremity of the green body, is a transparent chamber con- 

 taining a varial)le number of active molecules, measuring from 

 the twenty-thousandth to the forty-thousandth of an inch ; these 

 molecules or transparent spheroids, occasionally escape from this 

 chamber, and circulate vaguely and irregularly between the peri- 

 phery of the gelatinous body and the shell ; further, the parietes of 

 this chamber have a contractile power. The author denied the ex- 

 istence of any papilla) or proboscides at this part, as well as the sup- 

 position of Elnenberg that these moving molecules constitute the 

 basis of such papillsB. He also denied the statement of the same 

 • distinguished obsei-ver^ that if coloring matter was mixed with the 

 water in which the Closterium resides, any motion was communi- 

 cated to the particles of such coloring matter by the supposed pap- 

 illa*, or by the active molecules withm the terminal cells. A chcu- 

 lation of the fluids within the shell w^as obsei-ved, independent of 

 the vague movements of the active molecules ; this was regular, 

 passing in two opposite cun-ents, one along the side of the shell, and 

 the other along the periphery of the gelatinous body. When the 

 shell and body of the C/ostermm were broken by pressure, the green 

 gelatinous matter was forcibly ejected by the contraction of the 

 membranous envelope. 



" The action of iodine upon the specimens was very remarkable ; 

 1st, it did not, as reported by Meycn, stain the green body violet or 

 purple, but orange-brown ; 2d, it produced violent contraction of the 



