Evolution of Oxyrjcn hj Sca-JVccds. 255 



in a highly vigorous condition of vitality. It does not seem 

 easy to account adequately for the somewhat low percentage 

 shown in Experiments II. and VIII., but under ordinary 

 normal circumstances probably the general average stated, 

 viz., 50*8 per cent., may not be far from the truth. 



The high percentages of oxygen obtained in the above 

 experiments is very noteworthy, and demonstrate clearly 

 that the presence of the pinkish red colouring matter 

 present in the cells, and masking the green colour of the 

 chlorophyll, does not diminish their physiological activity in 

 this respect. As in the previous cases, all the specimens 

 experimented with were subsequently examined microscopi- 

 cally, some being kept alive in vessels of water for several 

 days. Spores were observed to be emitted only in three 

 instances, viz., in the first, second, and sixth ; the others did 

 not show this even after being kept alive for upwards of two 

 weeks. The general inference already stated is accordingly 

 substantiated in this case also, the occurrence of a maximum 

 period of vitality contemporaneous with a maximun of 

 physiological function being recognisable. That this has a 

 greater influence than the amount of sunshine occurring 

 during the period of exposure is also indicated by comparing 

 the percentages in Experiments I. and IX., since, on the 

 whole, more favourable conditions in this respect existed in 

 the latter case than in the former, yet the percentage of 

 oxygen in the one is much greater than in the other. 



Two points deserve notice in connection with this table — 

 (1) in nine of the specimens examined were spores observed, 

 notwithstanding the high percentage shown in the third 

 and fourth experiments ; and (2) the calculation of the 

 percentage has been divided into parts on account of the 

 large amount of gas collected. Thus in (Exp. I.) 83 c.c. 

 in all were obtained, of which 10 c.c. were taken for 

 determining the oxygen, its amount in the[remaining 73 c.c. 

 being calculated by proportion. Thus, by considering that 

 10 c.c. became 9-4 c.c. after correction, 73 c.c. under similar 

 conditions would become 68-6 c.c. ; and again, by observing 

 that 94 c.c. was reduced to 4-3 c.c, after pyrogallic acid was 

 introduced, it follows that 68-6 c.c. would be reduced to 31-4 

 c.c. Thus, in the whole 83 c.c. (the original volume), is 

 represented by 35-7 c.c. after the pyrogallic test. Hence it 



