THE BEGINNINGS OF IIFE. 507 



fact that in such a transformation the germ is almost 

 equal in bulk to the fully-developed animal to which it 

 gives birth. Again, at a later period (1859), in the 

 memoir to which I have so oft^n referred, Dr. Gros 

 frequently alludes to similar direct transformations of 

 large Euglen^ into Rotifers of the most varied nature 

 and size ^ He says that the Euglense which undergo 

 transformation gradually decolourize, and at the same 

 time the matter entering into their composition be- 

 comes more and more animalized 2. They either retain 

 the spherical form or else become slightly oval, whilst 

 the internal substance soon begins to exhibit contrac- 

 tions with traces of organization, and at last an embryo 

 Rotifer is distinctly visible ^, Elsev/here Dr. Gros 

 says 4 : — ' On voit done I'Euglene prendre la forme 

 ovalaire (PI. H, Fig. i), passer par la decoloration 



within closed filaments of Vaucheria — a fact which had been partially 

 indicated by linger in 1828. Speaking of the filament in which it 

 was contained, Morren says :— ' An attentive and lengthened observation 

 convinced me that in this there was no solution of continuity, and that 

 the arrival of the Rotifers within the Vaucheria was not at all to be 

 explained in this way. How are these parasitic animalcules generated 

 within them ? This is what further research has some day to show.' 

 (See Pritchard's 'Infusoria,' 4th ed. p. 46S.) Pritchard (p. 464) also 

 says that a form of Notommata has been found by Perty within the 

 filaments of a Vaucheria, and that another form of Rotifer {Albertia 

 vermicular is) is commonly found within the -intestines of earth-worms 

 and slugs. 



1 See loc. cit., pp. 332, 449; PL D, figs. 37-40, and PI. C, figs. 1-12. 



- Loc. cit., p. 307. 



3 See also loc. cit., pp. ,:;io, 314, 318. ^ 



* Loc. cit., p. 324. 



