361 
mals. The rudiments of the eye are present. The reciprocal of this cross 
was not attempted. 
In this cross many of the eggs stop their development at the closure of 
the blastophore with the main axis of the embryo laid down. Many of the 
eggs continue their development to a varying degree and with varying nor- 
mality. None of them, however, are developed in a perfectly normal man- 
ner. Among these embryos which live for a week or ten days, the most 
grotesque features appear. The yolk and embryo become pigmented, often 
very heavily, though not normally. On the yolk the pigment cells may be 
quite large, or quite finely branched, and they are likely to congregate in 
certain places, instead of having a distribution such as is found on the 
normal embryo. A favorite place for such congregation is on the surface 
between the very large pericardial cavity and the yolk where the pigment 
cells may densely cover the area. In the embryo the distribution of the pig- 
ment may be more or less regular. Thus along the dorsal side two rows 
may appear in the anterior portion, one on either side, these converging into 
a single median band running well out towards the posterior end. Both 
kinds of pigment cells, red and black, are well represented. 
The heart is always developed in these embryos and usually pulsates 
quite vigorously. The excessive development of the pericardial cavity which 
usually appears as a large clear vesicle—sometimes one-third the size of 
the yolk—has the effect of stretching the heart out to a great length. As a 
consequence a curious series of modifications obtain in the different embryos, 
from a relatively normal heart, although always more or less elongated, to 
strikingly aberrant conditions, in which the pulsating portion of the heart 
has become associated with the yolk bordering on the lower portion of the 
large pericardial cavity, and is a mere mass of cells without apparent 
structure, and connected with the upper border of the pericardial cavity 
near the embryo, by an extremely slender protoplasmic thread. No lumen 
can be detected in either portion and the only eftect of the rythmical and 
vigorous pulsations of the lower yolk portion is to stretch this filament, and 
pull the yolk upwards so that the latter rocks continually. The usual thing 
is for the heart to develop a cavity in the interior and the peristaltic pulsa- 
tions pass in the right direction. i. e., toward the embryo. Out of hundreds 
of such hearts, many of them relatively normal, which I have examined, 
I have never seen one carrying blood, certainly not blood containing red 
corpuscles. In regard to the rest of the circulatory system there is very 
