1921] NATURAL SCIENCES OF PHILADELPHIA. 135 



the amoeba and immediately were enclosed in a vacuole, soon dis- 

 appearing inside the body, sometimes the pseudopodia were the 

 means of capture, and the bacteria were seen to glide along them 

 towards the central plasma. On two special occasions, diatoms 

 were met with, nearly as long as the Chrysamoeba itself, and in 

 course of digestion. 



Such is the amoeba form of Chrysamoeba radians; but there is 

 another form, that of a typical Flagellate, which Klebs had already 

 seen and Scherffel afterwards described, only to doubt later his own 

 observation and believe in a confusion with another organism. 

 My observations, however, are such as to leave no obscurity. Chrys- 

 amoeba really passes through a flagellate state, or rather, one might 

 say, voluntarily abandons one state for another. I have made, 

 between December 29 and January 3, several experiments on the 

 subject, which all gave the same results, five colonies of Chrysamoeba, 

 nine, thirteen, twenty-four and fifty specimens in number respec- 

 tively, were isolated on five excavated slides in clear pure water, 

 and the amoebae were seen one after another to leave the jelly, 

 which after two, three and four days was quite free of any tenant, 

 while small Flagellata were swimming about. As an example, I 

 may give here a textual copy of the brief notes taken for the small- 

 est of these colonies: 



Dec. 29. 12 o'clock. Nine fine specimens in their jelly; not one of them 

 showing any flagellum; all are expanded as small star-like amoebae, 

 15 to 18^ in diameter. 

 4:30 o'clock. The same. 

 Dec. 30. 8:30 o'clock. Only four are left, a single one of them still in the 

 star form; the others are rounded, and two of them quivering; on one ot 

 them I can distinguish the slowly undulating flagellum. 

 9 o'clock. The undulations are more rapid. 



1 o'clock. Nothing is left in the jelly, and a small flagellated individual is 

 swimming about. 



On three or four different occasions, I was able to follow in one 

 single animalcule, from beginning to end, the passage to the fla- 

 gellated state. The amoeba slowly retracts its pseudopodia, then 

 becomes spherical, and begins quivering from time to time, but 

 without the flagellum, still too deUcate, being yet visible; but it 

 soon becomes distinct, and ten minutes after the first quivering 

 of the spherule, it is seen rapidly to vibrate at the anterior pole 

 of the now ovoid or pyriform animalcule; this latter then moves, 

 leaves the jelly, and goes in a straight course, revolving on its long 

 axis and swinging in a pendulum-like movement. 



