1896.] Acid in the Digestion of Certain Rhizopods. 621 
In most of the existing records of Protozoan digestion there 
are indications thatthe process shows irregularity in its outset 
and progress. It is not easy to foretell the immediate fate of 
ingested matter though of its ultimate fate there may be little 
doubt. There may be marked inhibition of digestive activity 
even after free ingestion. In plasmodia ingested nutrient 
matter may be actually discharged after very imperfect diges- 
tion. One of the most puzzling phenomena, however, that 
has been described by all observers in this field, has been 
termed by Greenwood and Saunders the stage of storage. 
This process consists in the preservation of ingested food 
masses, Which on first enclosure have been surrounded by 
liquid within a vacuole, in a shrunken seemingly very acid 
state. At times 100 non vacuolate, acid ingesta may lie within 
the substance of a vorticella, whilst active digestive solution is 
going on in other food vacuoles at same time. 
The storage of nutritious ingesta for hours and days in a 
condition in which acid indicators give evidence of an acid 
condition, whilst the same kind of nutritious material will 
undergo rapid digestive solution in an adjacent vacuole, nat- 
urally excites one’s curiosity. For a long time I had been 
looking in vain for some explanation of this phenomenon 
when an accident gave opportunity of viewing it in a new 
light. 
The plasmodia of a large mycetozoon, most probably Lam- 
proderma scintillans, had been under observation for about three 
weeks. Some of these amoeboid organisms were so large as 
to more than cover the field of vision when objective D and 
apochromatic eye-piece, No. 4 of Zeiss were used. They 
showed a habit of devouring everything in their vicinity in 
the ditch water in which they were cultivated, as a result of 
which they were at times so filled with debris that no accurate 
observations were possible. It was planned to transfer them 
gradually by pipettes into clearer and clearer water and by 
starvation compel them to rid themselves of the dirt they 
contained. This proved successful and after 8-18 days of 
transferring the plasmodia were in practically clear water, free 
from alge, infusorie, gregarines, bacteria, etc., and the usual 
