OF DENISON UNIVERSITY. 
2t 
that this chamber was that in which the blood-corpuscles (or, better, 
lymph-cells) were formed. The rectum is covered with irregular 
masses of cells of varying size, and I more than once thought to have 
observed their change to lymph-cells. It was impossible, unfortu- 
nately, in the time allotted to observe the development of the circu- 
latory system, but it would seem that the heart differentiates from the 
connective tissues between the stomach and the scutum. 
(Fig. 3 illustrates not only the formation of the posterior appendic- 
ular segments, but the rectal sinus with its muscles and lymph-cells. 
A simple valvular apparatus separates the rectum from the anterior part 
of the digestive tract. ) 
The next stage is illustrated on Plate VI, Fig, i. A change in 
proportion and in size is all that requires notice. Figures 3-6, illus- 
trate the growth of the appendages. Fig. 3 is the first foot of the 
right side of an individual over 1.5 mm. long. Fig. 4 is the same of 
a younger individual of which Fig. 5 is the sixth and Fig. 6, the ninth 
foot. Fig. 7 shows how the matrices of the caudal spines are devel- 
oped from enlarged cells as are the corresponding parts in Daphnia. 
Fig 2, of Plate VII, illustrates the general characters of the animal 
when about 2 mm. long. The maxilla have become larger and the 
feet begin to assume their definitive form. 
Fig. 3 shows the growth of the caudal stylets and the character of 
the valve at the opening of the anus, as well as the prolonged matrix 
at the setae. Fig. 4 illustrates the differentiation of the optic lobes 
and of the anterior part of the stomach. The heart is by this time 
well formed and whatever part the rectal cells may have played in 
originating lymph-cells, is lost. The liver lobes grow out from the 
stomach and the labrum becomes reduced. The antennae now un- 
dergo a rapid and remarkable transformation. In the male the shorter 
ramus becomes atrophied as shown in Fig. 10, and from the base an 
epipodal body is formed just as in the case of the feet. At first this 
pouch resembles homologous organs in the feet, but soon it alters and 
becomes greatly modified. In the female the change is similar, save 
that this branchial sac fails to develop (Fig. 9.) The palpus of the 
mandible is likewise reduced to a mere rudiment (Fig. 8.) 
The sexual organs of the female appear as lobed glands 
(Fig. 12.) The caudal stylets are of considerable size. A 
male, in the stage above mentioned, measures 3.5 mm. In the 
following stages growth is rapid. The antennae modify rapidly. 
