o92 EMERGENCE OP DRAfJONPLY-LAnViE, 



Series A has nut only l)een subjected to a serious limitation of 

 possible oxygen-supply to be derived from the water, but it has 

 been entirely deprived of any aid in this direction which the 

 plant-tissues might offer. Secondly, Series B, though presumably 

 partially restricted in its possible oxygen-supply from the watei-, 

 has the advantage of still being able to obtain some gas from the 

 surrounding plant tissues, assuming that such tissues play a part 

 in the oxygenation of the egg. Thus, Series B becomes a cwiUnd 

 upon Series A. Thirdly, Series C, placed under normal con- 

 ditions, plays the part of a control upon both Series A and B. 



At the start, I examined the eggs to determine to what stage 

 of embryonic development they had attained. T found that all, 

 except one, had just completed the revolution of the embryo. 

 This particular one was in Series A, and was kept under careful 

 observation. It finally yielded very remarkable results. As the 

 eggs of Ana.c papuensis normally take about three weeks to 

 hatch, I concluded that my eggs had been laid on or about March 

 7th, and had still ten or more days to go before hatching. At^ 

 first, I feared that development had proceeded too fai' already for 

 my experiments to yield successful results. Fortunately, how- 

 ever, this was not the case. 



On Man-h 'iTth, i.e., nine days after the experiments liegan, 

 I examined a large number of the eggs with special reference to 

 pidse. Those in Series C could not be well examined: but, as 

 one or two eggs in the less opaque tissues showed embryos with 

 the dorsal vessel pulsating fairly regularly, I concluded that all 

 was well in this series, and turned my attention to Series B. 

 Here, again, most of the eggs were not favourably placed for 

 observation, and I was compelled to reduce the amount of 

 vegetable tissue around several of the eggs to very small dimen- 

 sions. I then found that the emljryos appeared to l)e perfectly 

 healthy, with a pulse of about 70 per minute. Turning next to 

 Series A, I found that, in many of the embryos, I could not 

 detect any visible signs of heart-beat. In a few, the heart was 

 beating very slowly and intermittently — on an average, not more 

 than four or five times per minute. It was thus clear that 



