Notes on S pondylomorum Quaternarium Ehrenh. 
very beautifully the mulberry 4 ike habit of the colony, with its 
four alternating tiers of four cells each, as described by Stein; the 
cells loosely connected with one another by the interlocking of 
the long cilia (fig. i). Other preparations were made from 
material fixed in the usual way with Flemming’s weaker chrom- 
acetic-osmic mixture, embedded in paraffin, sectioned from three to 
six micra in thickness, and stained with Heidenhain’s iron-alum 
haematoxylin or with Flemming’s safranin-gentian violet-orange 
G. combination. Both staining methods yielded very good prep- 
arations, although those obtained by the triple combination 
gave, on the whole, clearer differentiation of the finer cell structures. 
No other methods of fixation or staining were tried. All the 
material for this study was fixed between the hours of sun-rise 
and eight o’clock on a bright morning, that of March 15, 1908. 
With preparations of living material the colonies present a some- 
what striking appearance as they move swiftly across the field of 
the microscope, rotating rapidly on their long axes. Evidently 
there is a strict coordination of movement among the different cilia 
of the various individuals of a colony, and a study of the behavior 
of these organisms would doubtless prove of great interest and 
value. In size the colonies are small, ranging according to their 
age from 15/1 (very young) to 35/^ (adult) in length, and from 12 m 
to 25/i in breadth. All the cells of a colony are alike in size, shape, 
and length of cilia. The individual cells are ovate in form, being 
somewhat more rounded in front and more pointed behind. The 
looseness of the union of the cells into the colony is shown by the 
numbers of individual cells which have become separated from 
the colony and are swimming about by themselves. The cells 
vary in size from 6.5 to 12// long, and from 3.5 to 6.5// wide. The 
cilia range from 22 to 35// in length. 
In each cell there is a single chromatophore of the Chlamydo- 
monas type, deeply cup-shaped, the bottom of the cup being thick 
and filling the entire hinder end of the cell, while around the mar- 
gin and extending forward it becomes very thin and shell-like. No 
pyrenoids are present. A red pigment spot is to be found on one 
side of the cell, usually not far from the nucleus. Two contractile 
vacuoles are present at the extreme anterior end of the cell, and 
these appear to contract alternately, as is the case with other mem- 
bers of the group. The nucleus is large and stands out very 
distinctly in well-stained preparations, surrounded by a region of 
