INTENSITY OF OXIDATION IN LIFE-CYCLE 205 
liberated 280, 800, 1250, 1725, and 1750 cc, and that the pupae, 
adult, and old bugs liberated 1800, 1750, and 900 cc. of oxygen^ 
respectively. 
By comparing these figures it may be seen that the unfertilized 
egg contains much less catalase than the fertiUzed. This is in 
keeping with the fact that the oxidative processes are much less 
intense in the unfertilized egg than in the fertilized one, as 
observed by Warburg. It may be seen further that the catalase 
content of a newly hatched larva is less than that of the older 
larvae in keeping with the fact that in the newly born, and 
presumably in the newly hatched, oxidation is very low and that 
it increases very rapidly shortly after birth. It may also be 
seen that the catalase content of the old bug is less than that of 
the younger adult in accordance with the fact that oxidation or 
metabohsm is less in a person of advanced age than in one in 
middle life. 
It should be mentioned in this connection that our observation 
of the low catalase content of the unfertilized potato-beetle egg 
and the high catalase content of the fertilized egg is in keeping 
with the observation of Winternitz (<5), who found that the 
unfertilized hen's egg showed no catalytic activity even after 
prolonged incubation, whereas the incubated fertiUzed egg 
rapidly acquired the power of decomposing hydrogen peroxide. 
They agree also with the observations of Battelli and Steam 
{6), who found that the catalase content of most of the tissues, 
and particularly of the liver, of newlj?- born pigs is lower than the 
corresponding tissues of the mother, but that the catalase activity 
rapidly increased, until at the end of the seventh or eighth day 
it was as high as that of the adult. 
J. Loeb (7) attributes the development of the fertilized sea- 
urchin egg to the increase in oxidation, and the increase in 
oxidation to a change in the cortex of the egg which makes the 
entrance of oxygen, and hence oxidation, possible, while R. 
Lilhe (8) holds that the cortical Isijev of the unfertihzed egg 
prevents the diffusion of COo from the egg and that this CO2 
prevents oxidation, and hence development. A more plausible 
explanation for the increased oxidation or metabolism in the 
