466 THE BEGINNINGS OF LIFE. 



of 1X28'^ that is to say, it had grown to one-third of 

 the length of the body of the organism. Gradually a 

 lateral extension of the oral cleft forms, and becomes 

 lined with cilia so as to perfect a form of Vorticella 

 (Fig. Z6^ g) similar to that which I have generally seen 

 proceed from the metamorphosis of an Euglena, 



Other transformations of Euglenae have been de- 

 scribed by Dr. Gros of a still more startling nature, 

 the consideration of which, however, it will be better 

 for us to defer for the present, until we have enquired 

 more fully into the evidence bearing upon the modes of 

 origin and life-history of the Ciliated Infusoria. But in 

 order to complete our list of the known changes which 

 Euglense may undergo, it will be desirable simply to 

 name the metamorphoses of these protean forms which 

 still remain to be considered. They are : — 



12. Transformation into Rotifers ; 



13. Transformation into Tardi grades ^ and 



14. Transformation into Nematoids. 



Remarks upon the various Modes of Origin of Ciliated 

 Infusoria. 



It has already been stated concerning almost all the 

 forms of Ciliated Infusoria which I have had occasion 

 to mention, that they may proceed, on different occa- 

 sions, from apparently dissimilar matrices; and also 

 that their mode of development is subject to much 



