326 THE SCOTTISH NATURALIST 



rate is indicated by the number of eggs deposited in the 

 cells formed, that is, 1-38 per day. 



At the period of maximum activity of the nest investi- 

 gated, 1159 eggs were deposited in 8 days in newly-formed 

 cells. Therefore the average number of cells built would 

 reach 145 a day. Here again the average number is well 

 within the limits of the height of activity, for the number 

 ought to rise during the 8 days with the increase in numbers 

 of the builders. 



As there were 417 workers in the nest, each worker 

 apparently built in a single day rather more than a third of a 

 cell (-348) — in other words, the building work accomplished 

 by 3 workers each day was rather more than a single 

 cell. This falls far short of the daily accomplishment of 

 the solitary queen, but it must be remembered that the other 

 duties of the nest — removing of soil for its extension, the 

 construction of the outer cover, feeding of the larvae — fall more 

 heavily upon the workers as the capacity of the nest 

 increases. 



Rates of Hatching. — At first the rate of hatching must be 

 extremely slow, corresponding closely with the rate of 

 oviposition when the queen works alone. During the first 

 31 days, no hatching takes place, and during the whole of 

 the second month of the nest's existence, the rate probably 

 averages less than 1-5 a day. Thereafter there is a gradual 

 but rapid increase as the effect of the increase in the 

 establishment begins to be felt. 



At the end of July there were in the nest in all 1234 

 pupae at all stages of development. In 10 days these would 

 have hatched, so that the rate of hatching would have 

 averaged 123-4 a day. But a month later, at the end of 

 September, the rate would have increased to approximately 

 that of the July oviposition, that is, to 186 a day. This rate, 

 as I have explained in discussing the average of oviposition, 

 is well within the limit, but the reduction will allow for those 

 eggs which fail to hatch and for the larvae which acci- 

 dentally fall out of the cells and fail to reach the pupal stage. 



Mortality amongst ]Vorkcrs. — The rate of mortality, 

 which will probably depend to a great extent upon the 



