62 | The West American Sctentisé. 
two pseudopods; the dendritic form is not developed for some 
time. The color granules of most of the cells are brownish- 
yellow; those of comparatively few cells being black. The cells 
are so large that they may readily be distinguished before any 
color is deposited in them. The term chromatoblast may prop- 
erly be restricted to them at this colorless stage. There are no 
chromatoblasts distinguishable when the embryonic shield begins 
to form; they first appear when the gastrula covers one-third or 
one-half the yolk. They are proliferated into the segmentation 
cavily from the embryo, where the latter joins the embryonic ring 
ana from here they migrate to various portions of the embryo. 
Just how they arise I cannot say, as means for sectioning are not 
athand. Further observations of living eggs may clear. this 
point. As the gastrula advances over the yolk they increase in 
number very rapidly, but, as far as I have observed, by the pro- 
cess of proliferation only. 
They are somewhat angular in shape, the angles being some- 
times prolonged into pseudopods. Their depth at this time is 
equal to that of the segmentation cavity. In their migration the 
pseudopods are usually foremost; amoeboid changes in shape 
were not observed, the whole cell moving forward. Most ofthe 
chromatoblasts are collected along the margin of the embryonic 
shield. When the embryonic shield narrows and the embryo 
becomes more definitely outlined the chromotophores rapidly mi- 
grate inward and cover the embryo, while others collect about 
the oil-globules and but few remain over the yolk. Shortly 
after the closing of the blastopore in Scieana the oil-globules 
unite and the eggs of this species can then be distinguished from 
those of Hypsopsetta only by the very slight difference in size. 
The chromatoblasts cannot be confounded with any other 
elements. They are approached in structure and position by 
the cells of the epiblast when about to divide. Such cells rise 
out from among the surrounding cells and project into the seg- 
mentation cavity, divide, and again sink to the ordinary level. 
As chromatoblasts cannot be observed continuously from their 
origin to the chromatophore stage, should this process extend 
over several days or weeks, it is not possible to say positively 
whether the color-cells of the genera Oligocottus, Isesthes, etc., 
have a similar origin. The fact that their genesis in so widely 
different genera as Hypsopsetta and Sciaena is identical, would 
indicate that the color-cells in all fishes are developed in a similar 
manner. Carl H. Ligenmann. 
* Preliminary Notice, 
CONTRIBUTIONS TO WEST AMERICAN BOTANY. 
In this series of papers it is proposed to present in a “connected 
form, such botanical observations as may be made by the writer, 
that may seem to contribute to a fuller knowledge of our West 
American flora, It is hoped that these may become worthy of the 

