462 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
plate (pi. 6, fig. 57) although I have not as yet been able to differ¬ 
entiate an achromatic spindle associated with it; following this 
stage there occurs a division and subsequent separation of the rod 
shaped bodies which may be provisionally designated as chromo¬ 
somes. A constriction which appears, finally divides the individual 
into two approximately equal parts, each part retaining usually three 
or four of the chromosomes (pi. 6, fig. 58-60). A vacuole surrounds 
these chromatin bodies at this time, so that in the rounded, living 
individuals, the refractive granules may be readily seen with highest 
powers, floating in the vacuolar fluid and showing Brownian motion. 
Such rounded, quiescent individuals are usually especially abundant 
in the early morning hours, from about twelve to twenty-four hours 
after the sowing of the spores. 
As sufficient data have not been obtained to warrant definite con¬ 
clusions concerning the complete changes, the details of the anaphase 
can only be conjectured. The occasional occurrence of single, elon¬ 
gated, twisted or U-shaped rods, leads to the conclusion that the 
several chromosomes become united again into a spirem (pi. 6, fig. 
60, a). The cytoplasm then probably encroaches on the nuclear 
vacuole so that the cavity finally disappears entirely, and, during 
the subsequent active amoeboid condition, the one or more chroma¬ 
tin bodies either become scattered and dispersed through the proto¬ 
plasm, or remain bound together (pi. 6, fig. 74-80). 
The active vegetating myxamoebae .— The second type of divi¬ 
sion mentioned above does not take place until after the myxamoebae 
have led a more or less prolonged active vegetative existence as inde¬ 
pendent individuals. For some hours following germination and the 
structural changes just described, the individuals remain quiescent, 
except for the slow movements of one or more contractile vacuoles. 
After a time, however, sluggish amoeboid movements become mani¬ 
fest, and the myxamoebae gradually assume the active vegetative 
condition. 
When actively crawling about, the myxamoebae of the various 
members of the JDictyosteliaceae^ frequently throw out delicate, 
usually pointed, pseudopodia, which extend sometimes to a length 
almost equalling that of the body of the individual (pi. 6, fig. 48). 
The very irregular shapes and delicate pseudopodia possessed by 
the myxamoebae of this higher group furnish a striking contrast to 
the more rounded or lobose amoeboid stages of the simpler species. 
