THE BEGINNINGS OF LIFE. 501 



the contracted mass of living protoplasm undergoes 

 processes of molecular rearrangement, varying in nature 

 at different times, but generally resulting in a transforma- 

 tion into other forms l . Thus it may undergo segmen- 

 tation into Monads or into Pythium corpuscles ; it may 

 emerge as a whole in the lower form of an Amoeba or 

 Actinophrys; or it may make its appearance as a totally 

 different Ciliated Infusorium : whilst we have now to 

 admit that on other occasions, as Dr. Gros long ago 

 pointed out, the encysted mass may undergo a totally 

 different set of molecular changes changes of a higher 

 kind so that ultimately it becomes converted into an 

 embryo of one or other of the small Rotifers. Such 

 a transformation, according to Dr. Gros, is liable to 

 occur occasionally amongst all sorts of Ciliated Infu- 

 soria. He says 2 : C I1 restera prouve aussi que les 

 Keroniens, les Dileptiens, les Oxytriques, les Coccu- 

 dines, etc., peuvent coconner (PI. O, figs. 13, 4, 5; 

 PI. P, figs, i-io), et donner naissance a des Rotatoires.' 

 Whilst elsewhere he says 3 : c Les Utriculeux derive's 

 des Euglenes passeront souvent les uns dans les autres, 

 et aboutirent quelquefois k des Rotatoires steriles pour 

 leur espece.' 



It has, moreover, long been known that the ap- 

 pearance of Rotifers in infusions is frequently preceded 

 by the presence of successive forms of Ciliated In- 



1 See p. 467, note r. 



2 Loc. cit, p. 456. 



3 Loc. cit., p. 299 ; see also p. 310. 



