PHYSIOLOGICAL EFFECTS OF LACK OF OXYGEN 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- 

 cal effects of the CO 3 . Even though everything indicates 

 that the action of CO 2 is qualitatively different from the 

 action of simple lack of oxygen, such differences have only 

 rarely to my knowledge, been demonstrated directly in the 

 cell. 1 In the egg of Ctenolabrus, however, these differences 

 are very striking. If freshly fertilized eggs are introduced 

 into a stream of pure CO 2 , no trace of cleavage occurs, even 

 though the eggs are not kept on ice. Under similar external 

 conditions the eggs kept in hydrogen divided two or even 

 three times. The germs also die much more rapidly in 

 CO 2 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 2 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. Amoeboid 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 

 a current 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 amce- 



i See LOEB AND HARDEST?, Pflilgers Archiv, Vol. LXI. 



