No. 2.] SPINNING ACTIVITIES OF PROTOPLASM. 375 
the processes, notably those which spun latest, are now gener- 
ally retracted. 
The whole aspect of things is as if the blastomeres were 
being drawn together by contraction of some of the threads. 
Moderate pressure upon the cover glass, slowly increased, 
tending to a mechanical forcing apart of the cells with more or 
less flattening, had a most curious effect, for it seemed rather 
to intensify and hasten the drawing together of the cells, and 
to increase the refractiveness of the threads, intensifying, rather 
than lessening, their optical characters. 
The threads were not seen to be drawn out into finer and 
less refractive filaments by such pressure,— as would naturally 
be the case were their nature purely physical, like that of the 
threads left when Bitschli forced apart masses of his viscid oil 
foams, — but, as stated, if the pressure were slow and moderate, 
they held and even emphasized their peculiar character. In 
finally giving way, as sometimes happened when the pressure 
threatened to rupture the cell walls, they broke short off and 
then rounded their ends in a viscid, mucilaginous-looking 
manner before retraction, which soon took place. 
Another curious fact was, that such mechanical pressure 
caused the egg to withdraw many peripheral processes, but 
seemed at the same time to increase, or re-stimulate, new forma- 
tions from the opposing surfaces of cells. Later, the peripheral 
spinnings were renewed with even greater activity if the pressure 
were taken away; or, in cases where the cells were forced apart 
and the membrane remained intact, it being very plastic under 
slow pressure, the peripheral spinnings were not only renewed 
at points over the entire surface, but extended themselves 
through unaccustomed distances until they reached the other 
cells. These results were best gotten in the 8-16 cell stage, 
— which seemed peculiarly to favor them. 
In the natural course of events in the typical, normal eggs, 
after the blastomeres were closely apposed to, or fused with, 
each other for a time, the same response to pressure was given 
by the cytoplasm of the new mass. /Pvessure seemed, in short, 
to increase the physical resistance of the mass to crushing stress. 
Since, if the cells so treated happened to be in that rhythmi- 
