1895.) Acid in the Digestion of Certain Rhizopods. 625 
investment of the enemy for a prolonged period, a new and 
interesting light will be thrown on this phenomenon. 
In the “Centralblatt fiir Bacteriologie, Parasitenkunde u. 
Infektions krankheiten, Vol. XIX, p. 785, Dr. C. Gorini de- 
scribes a method for cultivating Amoeba zymophila on a solid 
medium which in this case is the potato. It is certain that 
Amoebae will grow on old and new potatoes with alkaliniza- 
tion. This would offer an easy and convenient method of 
cultivating them. It should be emphasized that it is almost 
impossible to produce cultures of amoeba that are absolutely 
free from bacteria. A. Celli in the Centralbl. f. Bacteriologie, 
Bd. XIX, p. 587, describes a number of futile attempts to 
obtain such cultures. For our purpose it is not essential that 
the amoebic cultures should be absolutely free from bacteria, 
a relative, approximate sterility is sufficient to demonstrate the 
scarcity of storage vacuoles in the amoebae and plasmodia in 
such environment. Celli’s favorite solid medium is a prepara- 
tion made from Fucus Crispus with 5 per cent Sterilized Water, 
with or without Bouillon, but always made alkaline. To 10 c.c. 
culture medium, 1 c. c. of an 3 Solution of Potassium 
hydroxide, or 4-5 c. c. of a saturated solution of Sodium 
Bicarbonate. This culture medium of Fucus after it is made 
in the manner that Agar is generally prepared solidifies readily.. 
In the same Journal, Centrbl. fiir Bacteriologie, Band XIX, 
p. 258, Dr. M. W. Beyerinck describes a solid medium for 
amoebic cultures made from solidified agar by diffusion of 
the soluble organic substances in it into superimposed distilled 
water, which process requires about two weeks and repeated 
sterilization and subsequent addition of salts suitable to 
formation of nitrites. 
I have no experience with these methods and have always 
found that for my purpose a solution of a little wheat bread 
in distilled water kept in a small flat dish under a glass cover 
was all that was required to have Amoeba and plasmodia of 
mycetozoa constantly on hand. The dish must be kept on a 
little earth and not in too bright a light and at a constant 
temperature. This simple culture medium, which of course 
is unsuitable for pure cultures was suggested by Prof. Reichert 
of the University of Pennsylvania. 
