98 PROFESSOR O. BUTSCHLl. 



euchlorum, Ehrb., or, perhaps, with greater distinctness, the 

 zoospores of Colacium described by Cienkowski.\ 



Uroglena, Ehrenberg (' Die Infusionsthiere als vollkom- 

 mene organisraen/ Leipzig, 1838, pp. 61, 62, pi. iii, fig. 11). 



Uroglena volvox, Ehrenberg (loc. cit.). 



These organisms have been found by the author 

 in enormous numbers, chiefly in some small ponds 

 near Frankfort - on - the - Main, but also in a pond in 

 the Grand Ducal Park at Carlsruhe. They form large- 

 sized colonies, which are generally spherical, but never 

 so regularly spherical as in Volvox, since they generally 

 have more or less irregular blunt corners, and often deep con- 

 strictions. The individuals are ranged close to each other 

 (fig. 22 a), and are enclosed in a gelatinous covering ; the 

 author has not observed the tails described by Ehrenberg, 

 but finds that the hinder extremities of the individuals are 

 simply rounded, and that there is no junction between the 

 individual organisms. It is not yet determined whether the 

 spaces in the interior of the colony, which are not occupied 

 by the organisms, are filled with the gelatinous covering, or 

 with fluid ; but the author is inclined to think the latter, 

 since he has observed great numbers of diatoms and other 

 foreign bodies moving freely in this position. The greatest 

 length of a single individual is, on the average, 0011 mm. 

 Each individual bears two flagella peripherally, a large chief 

 flagellura tapering gradually from its point of origin, and a 

 small accessory flagellum near it, as in Dinobryon. 



The eye spot is close to the base of these flagella : the 

 author has only observed a single one, whilst Ehrenberg has 

 seen three, the increased number being due to impending 

 fission. 



In the anterior half of the body of each individual are two 

 yellowish-brown or greenish-brown pigment spots. Treat- 

 ment with alcohol extracts the bright green chlorophyll 

 colouring material from the pigment discs, just as in the case 

 of diatoms. The contractile vacuoles {v) are present singly 

 (fig. 23, a), they swell considerably during the systole, so 

 that the body wall has a hernia-like protrusion it contracts 

 rapidly and suddenly. The nucleus has been demonstrated 

 by carmine staining, followed by treatment with glycerine 

 containing hydrogen chloride. The process of reproduction 

 has not yet been followed out. 



' "TJeber Palmellaceen und einige Flagellaten," ' Arcb. f. Mikr. Anat./ 

 Bd. vi, 1S71, p. m. 



