42 NATURAL HISTORY 



lieve they are only attached by the posterior end of the 

 membrane of each globule^ having observed them in 

 pairs separate from the cluster. Their motion is some- 

 times rotatory, at others to and fro. Muller found them 

 among the Chara vulgaris. I found them plentifully in 

 the ponds at Hampstead. They congregate about the side 

 of the vessel in which they are kept. The diameter of 

 the clusters varies from 1 -400th to 1- 1000th of an inch : 

 a power of 200 is necessary to observe them distinctly, 

 but they may be discerned with a lens of a quarter-inch 

 focus, that is, a power of 40. Figure 15, in the en- 

 graving, represents a magnified cluster of these cu- 

 rious animalcules. 



32. VoLvox sphcBVula, The spherical Vohox, with 

 round internal molecules. — This animalcule is formed of 

 pellucid homogeneous specks of different sizes. It moves 

 slowly about a quarter of a circle in one direction, and 

 then returns. 



33. VoLvox lunula. The moon-shaped Vohox, — An he- 

 mispherical animalcule, composed of lunular molecules. 

 It is transparent, and the cluster is of the form shewn at 

 figure 18. The mass is in continual motion, turning 

 about in the water, while, at the same time, the indi- 

 viduals of which it is composed appear to change their 

 situation. They are found in marshes at the beginning 

 of spring. 



I am unacquainted with this animalcule, and am in- 

 clined to suppose it is merely a cluster of animalcules 

 coiled together indiscriminately. 



