XCiv THE BEGINNINGS OF LIFE. 



discus, digitata, viridis, and even the Actinophrys sol of some 

 authors, all of which are veritable Amoebae, to make it 

 evident that the rayed aspect does not suffice to characterize 

 this genus, and that we must seek for its determination 

 characters which are more precise/ 



In addition to this resemblance existing between Amcebce 

 in their encysted condition, and Actinophrys, it seems to be 

 quite certain that many Acinetce so closely resemble members 

 of the family Actinophryna that they are often mistaken for 

 one another. All the contradictory statements made by some 

 of the best observers as to the presence or absence of an 

 investing membrane in Actinophrys seem only explicable on 

 some such supposition *; though it seems extremely probable 

 that these several forms are separated by no distinct line, 

 and that transitions may take place from one to the other 

 type. According to Stein, indeed, there is an actual and 

 close relationship between Acinetce and Actinophrynce, since 

 both are looked upon as occasional developmental phases 

 of VorticellincB. Cienkowski, moreover, says 2 that the 

 organism described as Actinophrys by Ehrenberg is really a 

 non-pedunculate Acineta, and he also remarks that, although 

 numerous points of relation exist between certain Acineta- 

 forms and Podophrya fixa, he is unable to determine whether 

 they should be regarded as identical, or as extreme links in 

 the morphological cycle of one and the same species 3 . 



1 See Pritchard's ' Infusoria,' 4th ed. p. 244. 



2 ' Journ. of Microsc. Science,' 1857, p. 101. 



3 Cienkowski witnessed the process of fission taking place in Podo- 

 phrya. It was completed in about half an hour, and during this time 

 he states that he distinctly saw a temporary formation of cilia these 

 making their appearance and then disappearing after an existence 

 of twenty minutes. He says : ' During the process of division both 

 segments were furnished with tentacles; but when the oscillations 

 of the cylindrical portion commenced, very fine and short cilia might 

 be seen, though with difficulty, vibrating on the free end, the tentacles 

 at the same time being retracted and remaining visible only on the 

 posterior segment. I now followed uninterruptedly the movements of 



