446 THE BEGINNINGS OF IIFE. 



still presenting an embryonic appearance — in vessels 

 containing Euglense and Vaucheria. 



8. Transformation Into Desmids and Pediastre£, The 

 only Desmids that have been ascertained to be produced 

 by the transformation of entire Euglense, are those large 

 specimens belonging to the genus Closterium. Although 

 I have not myself had the satisfaction of witnessing this 

 transformation, Dr. Gros states that he has observed it 

 on several occasions. The particular modification of 

 the Euglena which is occasionally apt to undergo this 

 change is, however, quite familiar to me. Specimens 

 are frequently to be observed which, having lost their 

 flagellum, are prone to assume an elongated worm-like 

 form. They crawl, too, in a slow worm-like manner, 

 rather than swim • and are always noticeable on account 

 of the extreme brilliancy of the well-formed green 

 vesicles which they contain, and of the bright carmine 

 colour of their so-called ^ eye-speck.' After a time, their 

 movements grow more and more languid^ and the 

 green vesicles separate from one another at the middle 

 of the body {e)^ so as to leave a clear space similar to 

 that which also exists to a certain extent in the various 

 forms of Closteria — into one or other of which these 

 languid and elongated Euglense may, according to Dr. 

 Gros, be gradually transformed. The transformation 

 sometimes takes place in a few days, and sometimes 

 only after two or three weeks j whilst other specimens 

 of the same kind of Euglense may remain, even for 

 months, without undergoing any noticeable alteration ^ 



^ See loc cit., p. 317. 



