146 DESCRIPTION OF [Polxjgastrica. 



tracts also upon the action of certain re-agents, whose 

 effects cannot be considered purely chemical. 



" 3rdly. The comparison of the supposed ova with the 

 cytoblasts and cells of plants precludes the possibility of 

 our considering them as the latter, while the appearance 

 of a vitelline nucleus, transparent but molecular fluid, 

 a chorion or shell, determines them as animal ova. It 

 was shown to be impossible that these eggs had been 

 deposited in the empty shell by other infusoria, or that 

 they were the produce of some entozoon. 



" 4thly. That while it was impossible to determine 

 whether the vague motions of Closterium were voluntary 

 or not, yet the idea the author had formed of a suctorial 

 apparatus forbad his classing them with plants, 



" Lastly, in no instance had the action of iodine pro- 

 duced its ordinary effects upon starch or vegetal)le matter, 

 by colouring it violet or blue, although Meyen asserts it 

 did in his trials." 



The author therefore concluded that Closterium must 

 still be retained as an infusory animal, although it is 

 more than doubtful whether it ought to rank with the 

 polygastric families. 



Genus XXXI. Closterium. The spindle Animalcules. — 

 This genus comprehends all the known members of the 

 family ; the characteristic features of the latter, therefore, 

 answer for the genus. Twenty-seven species have been 

 described, although but sixteen are clearly determined. 



104. Closterium lunula {Vibrio lunula, M.) The 

 half-moon-shaped Closterium. — Lorica smooth, crescent- 

 shaped or straight, attenuated and rounded at the aj^ices. 

 Glandular substances scattered over the interior of the 



