216 Dr. C. Shearer. On the Oxidation Processes of 



or below this, that a great difference is made in the solubility of CO2 in sea- 

 water. Tensions of this order never obtained in the chambers of the mano- 

 meter under the conditions of the following experiments. In the following 

 experiments no special importance was attached to the carbon dioxide measure- 

 ments beyond determining roughly the relation of the carbon dioxide output 

 to the oxygen consumption. No trouble was taken, therefore, to determine 

 the C0 2 output with any degree of accuracy. It is clear that it follows the 

 oxygen consumption very closely, the respiratory quotient being always in 

 the neighbourhood of 0'9. 



To absorb the carbon dioxide in the oxygen manometer, a drop of KOH 

 was placed in the small cup in the bottom of the chamber stopper, and this 

 was renewed after each experiment. 



The manometers were made to clamp on a mechanical shaker, such as that 

 used when the instrument is employed for making blood-gas determinations. 

 The motion of this shaker had to be slowed down very considerably into a 

 very gentle to-and-fro motion, or otherwise considerable injury resulted to 

 the egg-membrane. Any injury to the egg-membrane always results in an 

 immediate and abnormal increase of the oxygen consumption of the egg. It 

 was also found that the conical pointed type of chamber with which the 

 instrument is furnished for blood-gas work was highly unsuitable for egg 

 work. The eggs tend to crowd down in the narrow end of the bottle and 

 there clump together, and fertilise very badly. The conical chamber was 

 therefore replaced in the following experiments by a more or less spherical- 

 ended pattern. In making a determination, invariably 2 c.c. of eggs in sea- 

 water were placed in one chamber, while the same quantity of plain sea- 

 water was placed in the control chamber. The chambers were then attached 

 to the manometer and half submerged in the water of the thermostat ; a drop 

 of very dilute fresh sperm was then introduced by a fine pipette into the 

 tube in the stopper of the chamber containing the eggs, through a small 

 opening in the top of the stopper. AVhen the glass plug closing this opening 

 had been replaced, the chambers of the manometer could be completely 

 stibmerged in the water of the thermostat with the stop-cocks open. It teas left at 

 least 20 minutes with the shaker working, to come into complete eqiiilibrium with 

 the temperature of the water of the bath. 



If the eggs are not properly cooled to the bath temperature, or if the sperm, 

 when run down on the eggs, are at a different temperature from the eggs, 

 faulty manometer readings will be obtained. To avoid any such errors in the 

 present experiments, great care was always taken to have the eggs, sperm, 

 and manometer, all at exactly the same temperature as the water of the 

 thermostat tank before commencing an experiment. The eggs and sperm, 



