PHYSIOLOGICAL EFFECTS OF LACK OF OxyYGEN 393 
VI. THE EFFECT OF CARBON DIOXIDE UPON THE PROCESSES OF 
CLEAVAGE IN THE CTENOLABRUS EGG 
If eggs are introduced into a current of pure carbon dioxide 
(which has been carefully washed), we must expect to obtain, 
besides the effects of mere lack of oxygen, the specific chemi- 
eal effects of the CO,. Even though everything indicates 
that the action of CO, 1s qualitatively different from the 
action of simple lack of oxygen, such differences have only 
rarely to my knowledge, been demonstrated directly in the 
cell." In the egg of Ctenolabrus, however, these differences 
are very striking. If freshly fertilized eggs are introduced 
into a stream of pure CO,, no trace of cleavage occurs, even 
though the eggs are not kept onice. Under similar external 
conditions the eggs kept in hydrogen divided two or even 
three times. The germs also die much more rapidly in 
CO, than in hydrogen. This constitutes, however, only a 
quantitative difference. A qualitative difference evidences 
itself, however, immediately that the air is replaced by a 
current of CO, in eggs in the two- or four-cell stage. In 
these experiments the eggs were kept in a drop of sea-water 
in an Engelmann gas-chamber. Amceboid movements (which 
were first noticed at the periphery of the drop) took place on 
the surface of the eggs in some ten to fifteen minutes, when 
acurrent of carbon dioxide was passed through the cham- 
ber. Whether the whole protoplasm or only the superficial 
layer of the protoplasm takes part in these changes could” 
not be determined. I have made a series of camera draw- 
ings of these movements, which I will reproduce here. 
Fig. 118 shows the outlines of the four cells of an egg at 
the beginning of the experiment. Fourteen minutes later this 
cell had the appearance shown in Fig. 119. One of the four 
cells, that which was directed toward the periphery of the drop 
and first struck by the stream of carbon dioxide, sent out ame- 
1See Lors anD HaRpESTY, Pfliigers Archiv, Vol. LXI. 
Digitized by Microsoft® 
