CJosterina.'] INPUSOP.IAL animalcules. ISl 



and granular body, infosted by a highly elastic and conh"actilc 

 membrane, which is attached by variable points to a hard siliceons 

 shell." This lorica, Mr. C. Varley states, will resist even the action 

 of boiling nitric acid. " The form of Closterium is spindle-shaped or 

 crescentic, the shell consisting of two horns, tapering off more or 

 less to the extremities, and united at the central ti'ansverse line, 

 constituting a perfectly syramctrical exterior. At the extremit)^ of 

 each horn is an opening in the shell, which, however, is closed "wdthin 

 by the membranous envelope — wanting, however, in some specimens. 

 Within the shell, and at the extremity of the green body is a trans- 

 parent chamber, containing a variable number of active molecules, 

 measuring from the 20,000th to the 40,000th of an inch ; these mole- 

 cules, or transparent spheroids, occasionally escape from this chamber, 

 and cii'culate vaguely and iiTcgularly between the periphery of the 

 gelatinous body and the shell. Further, the parieties of this 

 chamber have a contractile power." The author denied the 

 existence of any papillae or proboscides at this part, as well 

 as the supposition of Ehrenberg, that these moving molecules con- 

 stitute the bases of such papillae. He also denied the statement of 

 the same distinguished observer, that if colouring matter was mixed 

 with the water in which the Chsterium resides, any motion waa 

 communicated to the particles of such colouring matter by the sup- 

 posed papillae, or by the active molecules within the terminal cells. 

 A circulation of the fluids within the shell was observed, independent 

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

 passing in two opposite currents, one along the side of the shell, and 

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

 shell and body of the Chsterium was broken by pressure, the green 

 gelatinous matter was forcibly ejected by the contraction of the 

 membranous envelope. 



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

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

 purple, but orange brown : 2nd, it produced violent contraction of 

 the investing membrane of the body, whereby the green matter was 

 often forcibly expelled from the shell at the transverse division ; it 

 instantly annihilated the motion of the molecules in the terminal 

 sacs, and the sacs themselves became so distended with fluid as to 



