FERTILISATION 191 



difference between the eggs treated with acetone and the untreated 

 could be observed ; both consumed almost the same quantity of 

 oxygen. In the case of the fertilised eggs there was again, as with 

 the eggs rubbed with sand, an enormous drop in the respiration. 

 The eggs after treatment with acetone can even be dried, when they 

 can be reduced to a very fine powder. This powder, when dissolved 

 in water, still shows considerable respiratory power. The unfertilised 

 acetone egg powder, however, shows almost as much consumption of 

 oxygen as the intact egg, while the fertilised acetone egg powder 

 shows a drop of over 90 per cent, in its power of consuming oxygen. 

 None of these egg powders give off C0 2 . 



In the more recent work on the oxygen consumption of the egg, 

 the Winkler titration method has been superseded by the more 

 accurate and convenient Barcroft differential manometer method. 

 The advantage gained by the use of the manometer is that continuous 

 observations can be made on the same material, and the respiratory 

 exchange can thus be followed minute by minute. 



Warburg 1 (1915), using this instrument, has made a rein- 

 vestigation of the respiratory exchange of the egg of Stronglocentrotus 

 during the first twenty-four hours of development. He found that a 

 quantity of unfertilised eggs that contained 20 mg. of nitrogen, at a 

 temperature of 23 C. consumed 10-14 cubic millimetres of oxygen 

 in twenty minutes. The fertilised egg, ten minutes after the addition 

 of the sperm, consumed 60-84 cub. mm. under the same conditions. 

 That is, ten minutes after fertilisation the oxygen consumption of the 

 egg was 6 times greater than before fertilisation. In the sixth 

 hour the oxygen consumption was 12 times that of the unfertilised 

 egg, at twelve hours 16 times; while at twenty-four hours it was 

 22 times the amount of the unfertilised egg. As Warburg states, 

 it is highly remarkable that in one and the same cell substance, 

 which receives no addition of fresh material from any external 

 source, we should find, as the result of fertilisation, in the course of 

 twenty-four hours a rise in its oxidation rate equivalent to some- 

 thing like 2,000 per cent. 



On the whole the manometer seemed to show that there was a 

 much closer agreement between the increase in the respiratory 

 quotient and the growth of visible structure of the egg. In all 

 instances the CO 2 output of the eggs follows the oxygen consumption 

 very closely, the respiratory quotient being about 0'9. The respira- 

 tion of a single spermatozoon was found to be 1,500-2,000 times 

 smaller than the egg. 



In the past season the investigation of the problem has been 



1 Warburg, "Notizen zu Entwicklungsphysiologie des Seeigeleies," Arch, 

 f. ges. Physio!., vol. clx., 1915. > , 



