466 PROCEEDINGS : BOSTON SOCIETY NATURAL HISTORY. 
endeavoring to determine the relationships to the latter, I have 
introduced various species of bacteria into the hanging drop culture 
and have noted the behavior of the mj^xamoebae towards them. 
The bacteria are often caught by jDseudopodia, and held while their 
free ends swing back and forth; or, one end of the rod may adhere 
for a time to the mucus or ectoplasmic film of the myxamoeba and 
then again become free (pi. 6, fig. 87). What appeared to be 
ingestion has, however, been observed in comparatively few cases. 
In a few instances, where the conditions for observation were 
especially favorable, the rods were seen to be engulfed by an 
infolding of the hyaloplasmic border. I have, however, several 
times observed vacuoles in which one or more undoubted bacteria 
were present, and in others, granular substances which might possi¬ 
bly be regarded as bacteria in course of digestion have been 
repeatedly observed. But I have never, in fact, even after long 
observation, seen any changes whatever in ingested particles, and I 
have consequently been inclined to regard the minute granular 
material enclosed in vacuoles, not as ingested bodies, but rather 
either as the scattered chromatin or as waste products in the cell. 
As the difficulties of keeping any one myxamoeba under observation 
for several hours are very great, the changes which may take place 
in a certain ingested particle have never been traced as far as its 
assimilation into the protoplasmic substance, if, indeed, such changes 
occur at all. Conclusive evidence that certain of the internal gran¬ 
ules are bacteria is furnished, however, by staining with such differ¬ 
entiating stains as Flemming’s triple stain or acetic gentian violet. 
The bacterium, surrounded by a clear vacuole, will thus be clearly 
differentiated from the other included granules, which it may 
resemble somewhat in shape (pi. 6, fig. 88). Furthermore, in the 
living myxamoebae, rods precisely like those of the colony of 
bacteria which may be near, or even the comparatively large spores 
of Dictyostelium or other species, may be occasionally observed, 
carried about in the protoplasm of the crawling organism (pi. 6, fig. 
86). If bacteria are sown near a transfer of the spores of any of 
the Acrasieae, the myxamoebae which have just become active after 
germination soon crawl within the limits of the developing colony 
and remain for some time almost quiescent, showing more sluggish 
movements, while they assume a more rounded shape than the 
usual irregular one. The significant fact that within the limits of 
