1896.] Acid in the Digestion of Certain Rhizopods, 619 
ON THE ROLE OF ACID IN THE DIGESTION OF 
CERTAIN RHIZOPODS. 
By Jonn C. Hemmeter, M. D., 
In the “ Annales de l’Institut Pasteur,” for 1890 and 1891, 
there are two papers by M. Felix le Dantec on “ Researches on 
the intracellular digestion among the Protozoa,” which are de- 
tailed accounts of systematic experimentation concerning the 
occurrence of acid in the digestive vacuoles of Protozoa. 
In 1889, E. Metchnikoff published a discussion of the reac- 
tion of plasmodia to ingested litmus, also in the “ Annales de 
PInst. Pasteur.” 
Miss M. Greenwood and E. R. Saunders, in the “ Journal of 
Physiology,” Vol. XVI, 5 and 6, 1894, have published an ex- 
haustive account of the function of acid in Protozoan digestion, 
of which the following brief abstract is considered necessary 
before proceeding to the original part of this report. 
It was found that while these protozoa ingest solid matter 
constantly and promiscuously, such matter has a determinate 
fate. If it is innutritious it is ejected after lying in contact 
with the animal’s substance for a length of time which varies 
with many changing conditions. Nutritious matter, on the 
other hand, during enclosure in food vacuoles undergoes pro- 
found change, and this change is effected by something passed 
out of the protoplasm into the vacuole, acting in a fluid me- 
dium and by its presence making that medium deserving of 
the name “secretion.” In Actinospaerium, also, and in Amoe- 
ba proteus, digestion in like manner is effected, not by direct 
contact with the acting protoplasm but by some constituent of © 
a fluid, the formation of which the presence of food alone is 
potent to bring about. These protozoa depend upon the solu- 
tion of proteid for nourishment. Starch undergoes no diges- 
tive change, and the value of ingested fat globules i is doubtful. 
The following is a report on the role of acid in these diges- 
tive vacuoles. For method of observation, it may be briefly 
1 Phil. D. Etc. Baltimore, Md. 
