376 ANDREWS. PVOE. XDI: 
cally somewhat relaxed state between cleavages, they rounded 
themselves up under intermittent pressure instead of flatten- 
ing ; it is thought that the peripheral substance was instru- 
mental in these changes. 
After two sister cells are in close apposition to, and what may 
now, perhaps, be called safely, physiological union with, each 
other, there is offered to mechanical pressure an emphatic, and, 
if the pressure be slowly augmented, an increasing resistance. 
I found that shaking also increased the resistance to pressure. 
In making these pressure experiments I used a large, screw- 
adjustment compressorium, making marks upon the head of 
the screw and upon the supporting plate to estimate in a rough 
way the relative amounts of pressure. No doubt special devices 
for this purpose would bring to light an important series of 
differences. 
After re-union of the first two blastomeres to form what 
may be termed a dual mass, matters progressed in the usual 
rhythmic way towards the second cleavage. During this time 
the spinning phenomena were persistent over the general 
periphery, the processes being longer and extending themselves 
to greater distances, which they may easily do because of in- 
crease in size of the egg membrane. 
It may be difficult to convey a true idea of the extreme deli- 
cacy of these spinnings from the egg pellicle. In attempting 
camera drawings, I found that even a fine needle point came 
much in one’s way in efforts to follow their outlines. There 
were local thickenings and differences of aspect which could 
not be portrayed so at all, and the chief meaning of these lay 
in their very evanescence. The only way seemed to be, to 
receive as truthful and passive a brain photograph as possible, 
and. to translate this into terms of permanent line and shape, 
getting with the camera a skeleton of relative lengths and gen- 
eral local character of the lines of living substance. 
The rays showed all the characteristic differences known in 
Heliozoan rays; and when one says this, much is said of many 
variations. They were freely produced and as freely returned 
to the substance of the pellicle from which they arose. 
All the while, the alveolar structure, which was clearly 
