I)i. H. M. Vi 



only ten hours at 22 were apparently not aH'e<.-tf<l. A- .subsequent 

 ; vaults will show, this was doubtless due to some error. Those from 

 ova kept from the end of the 1st to the c-iul of the 28th hours were, 

 liiixvcvcr, increased nearly 11 per cent., or on an average 0*40 per 

 cent, per hour for each of these hours. The larvae from ova kept 

 seventy hours at 22 were increased by about 16 per cent., so the ad- 

 ditional forty-three hours produced an extra increase of 5 - 39 per cent. 

 On an average, therefore, the increase during the 29th to 71st hours 

 amounted to only (H25 per cent, per hour, or less than a third as much 

 as for the earlier period. 



In the next experiment, made in April, the temperature of the tank 

 water was 13'8. In this case we see that by keeping the developing 



ova during the 1st to 8th hours at 23, the larvre were increased 7*0 

 per cent, in size, or T08 per cent, per hour. For the 1st to 19th hours 

 the increase was 1 1 '6 per cent., or, on an average for the 8th to 19th hours, 

 0'37 per cent, per hour. Again, therefore, the increase per hour for the 

 later period is only about a third that for the earlier. After the 19th 

 hour, apparently no further increase in size was produced. Probably 

 this is an error, but in any case the effect must have l>een very slight. 

 It should be pointed out that there is probably in almost every case a 

 possible experimental error of some 2 per cent, in the determination of 

 the growth of these larvae, and occasionally, as we saw in the preced- 

 ing experiment, this error may for some unknown reason Ije consider- 

 ably greater. 



In the next experiment only approximate results can be calculated. 

 Thus larvae were grown at respectively 13-3 and 20'3 during the 

 whole period of development, but some of them were also preserved 

 and measured after only 3i days' growth. The following values were 



obtained : 



3J days. 8 days. 



Keptatl3-3 88-28 100 : 00 



20-3 . 109-63 111-98 



Here we see that the larva? grown only 3 days at 20-3 are 9 -6 3 per 

 cut. larger than those grown 8 days at 13'3. If they had been kept 



