914 
METHODS OF REPRODUCTION AND LIFE CYCLE. 
It seems fairly certain that there are at least three, and perhaps four 
methods of reproduction of amcebe, but whether or not some or all of 
them are common phenomena of the same amoeba, or whether they are 
different in different species it is difficult to determine. 
In cultures, simple fission is easily observed and it is a common 
property of all amcebe which we have studied. A second phenomenon, 
somewhat resembling the above, but which is much more rarely seen, 
is that of budding, by which a small portion of the amceba is separated 
from the parent parasite apparently without interfering in any way with 
the motility or other evidences of life of the original organism. In more 
than one instance we have seen two of these buds given off in succession 
before we lost sight of the parent. 
A third form is that following encystment of the parasite.’ Encyst- 
ment, under certain circumstances, is the property of many, if not of 
all, amcebe, and of course further reproduction occurs from the cysts. 
In many cases this certainly takes place by some process of sporulation, 
sporogony, or schizogony. In others another method, to be mentioned 
below, appears to result. 
We have never been able actually to observe sporulation, although 
cultures of encysted amcebee shortly after transplantation to fresh media, 
contain vegetative forms which often are exceedingly small and numerous. - 
Apparently another method of reproduction, or revegetation, occurs 
from the encysted stage. In this a single, motile amceba escapes from the 
ruptured cyst. We have observed this phenomenon a number of times 
in cultures, and believe the observation to be accurate. A number of 
changes take place before this process is completed, and among them we 
have noted an increased activity of small granules within the encysted 
amoeba, and these granules, while still in active motion, become arranged 
around the periphery, while the nucleus becomes more prominent. ‘The 
cyst wall then changes to a less dense and more transparent consistency. 
Finally, it ruptures and a motile amoeba escapes. The old cyst wall 
remains for some time as a foreign body in the culture medium. 
Lastly, we have cultivated two amcebe which do not encyst even in 
cultures several months old. One of these has now been in artificial 
media for about two years and only lately has begun to form imperfect 
cysts. 
MORPHOLOGY, CLASSIFICATION, ETC. 
In addition to differences in the methods of reproduction, other distine- 
tions between amcebee have been described from time to time. ‘These relate 
to practically everything which may be observed from the study of any 
one of these parasites. They refer to: 
(a) Amebe as a whole.—Size, color, shape, and motility. Number, 
size, shape, and contents of pseudopodia. 
* Perhaps there are other forms of reproduction as well. 
To ae ae Pee 
