Pkilodtiiaea.} infusokial animalcules. 669 



one or the other of their extremities, here and there, at different 

 distances from the summit, protuberances of a chivate form, more or 

 less regular, straight, or slightly bent back ; and others on the sides 

 of the stallc, which have the form of a capsule, or vesicle. These 

 vesicles are, at fii'st, of a uniform bright green colour, and without 

 increase of size, which exceeds several times that of the branches ; 

 they always become of a blackish-green colour, darker towards the 

 base, and then one or two globules, of a reddish-brown, may be 

 clearly distinguished there, often surrounded by smaller granules, 

 evidently destitute of motion, \^hilst the great ones move spontane- 

 ously and slowly, here and there, in the interior of the capsule, by 

 unecjual contractions and dilatations, whence arise remarkable changes 

 of form. I saw these globules at the end of eight or ten days after 

 their appearance, still inclosed in the capsule, moving more and 

 more slowl}', receiving no very decided increase, whilst the base of 

 the capsule became more transparent ; at last I observed that, instead 

 of their expulsion, which I was watching for, the extremity of the 

 capsule, at the end of some days, took an angular form, and sub- 

 sequently gave birth to two expansions, in the form of horns ; it 

 remained in this state, and became more and more pale, whilst the 

 animalcule became darker, and died, and afterwards it ended by 

 perisliing at the same time as the other parts of the conferva.' 



" Subsequent researches have not succeeded in informing us what 

 this animal might be of which Unger spoke. As this author th'ew 

 so much attention to the spontaneous movement of the propagula 

 spores of the Vaucheria, and as he admitted the passage from vege- 

 table life, characterized, according to him, by immobility, to animal life, 

 the principal criterion of which was motion, his animalcule was con- 

 founded with the propagula; and no one, so far as I know, has 

 returned to this very interesting subject. 



"When, therefore, I found the Vaucheria clavata at Everghem, I 

 was as much siu'prised as pleased to see the mobile body, noticed by 

 Unger, better than he did : with the aid of a higher magnif3dng 

 power, I found it easy to ascertain the true nature of the animal, for 

 it was not a propagulum, but a real animal, the Rotifer vulgaris, with 

 its cilia, wheels, tail, *S;c, 



" The urst protuberances, or vesicles, which I saw, containing this 



