OF HETEROGENESIS 217 



serve as food for the young Amoeba, which consequently attain 

 altogether larger dimensions. The inequality in size is very marked 

 in B. 



In all the cases where this kind of change is taking place I have 

 observed again, as on previous occasions, that there is a more or 

 less thick layer of motionless Bacteria outside and between the 

 Amoebae, and, of course, on the inner side of the wall of the cell, 

 while the surface of the wall is thickly flecked with a number of 

 curious glistening white specks, such as may be seen in Fig. 38, C. 

 A little above the proper focus these specks look black instead of 

 white. Another interesting point is shown by this specimen. It 

 was taken from one of the larger sub-terminal cells, in which the 

 chlorophyll corpuscles were larger than they are in the minute 

 terminal cells, and many of them also contained rather large starch 

 grains, such as are common within the chlorophyll corpuscles. 

 Several of such grains may be seen, still undigested, within the 

 Amoebae into which the chlorophyll corpuscles have been converted. 

 It cannot be supposed that the starch grains are now in the 

 Amcebas, because the latter have swallowed the entire chlorophyll 

 corpuscles. There was not the least evidence of this, and, more- 

 over, the small size of the Amoebae forbids such a notion. 



(h) Transformation of the Substance of Euglenae into 

 Peranemata.' 



The change of Euglenae into Peranemata has been followed 

 on several occasions, but I have never seen such multitudinous 

 examples of this transformation as occurred in a pellicle composed 

 of large Euglenae, brought from the small lake near Loughton — 

 when thousands were seen undergoing this change ; just as others, 

 equally numerous, were becoming converted into Amoebae in the 

 rhanner shown in Fig. 35. These two changes occurred during the 

 same period. They were first recognised about ten days after the 

 pellicle had been obtained, and when the Euglenae were all encysted. 

 The two transformations sometimes occurred side by side, but the 

 change into Amoebae took place most abundantly in a portion of 

 the scum which was floating on water in a deep bowl, while the 

 change into Peranemata was most common in portions of the scum 

 that had been placed in a shallow saucer. 



The beginning of the change into Peranemata is shown in 



' These are organisms something like colourless Euglenae, though provided 

 with a much stouter flagellum. 



