R. T. Wells 
213 
gested. In specimens fixed with osmic acid and stained by Giemsa’s 
solution the blunter pseudopodia are well demonstrated (PL VI, fig. 14). 
After its escape from the cyst the amoeba continues to move more 
or less actively over the surface of the fresh medium, leaving a trail of 
bacteria in its wake. Actively motile amoebae of this type have been 
watched on 12 occasions for periods of from 1-6 hours without showing 
any radical change in their behaviour. On the other hand, on nine 
occasions, an amoeba under examination was observed to shrink and 
assume a rounded or oval form (PI. VI, fig. 6), then the body undergoes an 
hour-glass constriction and finally divides into two daughter amoebae, 
each approximately half the size of the parent (figs. 7 and 8); the 
whole process from the first evidence of constriction till complete 
division takes about two minutes. 
The process of nuclear division was not followed hi fresh specimens; 
indeed I have found the behaviour of these amoebae, while undergoing 
fission, to be in this respect similar to that observed by Liston in one 
strain of amoebae isolated by him from liver abscess pus. As in the 
amoeba described by Liston, on the condensation of the plasma previous 
to division, the nucleus becomes obscure, nor in the new daughter 
amoebae is a nucleus immediately to be seen ; it takes shape gradually 
and not till 2-5 minutes after division does it become clearly visible. 
In stained specimens, some amoebae were seen in which the nucleus, 
while taking the stain deeply, showed an appearance suggestive of 
simple fission (PI. VI, fig. 15); in none was evidence of karyokinesis seen. 
In one stained specimen (fig. 16), an amoeba was seen showing an 
hour-glass constriction in the middle with a clear vacuole at each pole, 
withoiit distinct nuclear staining. 
In fresh specimens, on many occasions a small portion of a motile 
amoeba was seen to become detached, these fragments showed no active 
movement and ultimately disappeared from view after half an hour or 
more. On four occasions however true motile buds, 2-5 /jl in diameter, 
were seen to emerge from the parent body. 
In specimens fixed by corrosive-alcohol-acetic acid and stained by 
iron-haematoxylin, an amoeba is often seen to contain one to 12 or more 
clear rounded spaces 1 to 4 /i in diameter, with or without a central 
or eccentric dot which takes the chromatin stain faintly (figs. 17 and 18); 
these apparently correspond to the “ internal buds ” or “ merozoits ” 
of Noc. 
Many small protoplasmic masses, one or more /i in diameter, some 
containing a distinct nucleus, othei’s without any chromatin staining. 
