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THE SCOTTISH NATURALIST 



I therefore adopt as a basis for calculation, taking the 

 periods of 8 and lO days as the development period for 

 eggs and pups respectively, and the average period of 

 13 days for the larvje. Readers need not be reminded that 

 calculations based on these data can be regarded only as 

 approximating more or less closely to the actual facts ; for 

 as the contents of this nest themselves show, the fluctuations 

 of weather have almost certainly some bearing on the rate 

 of development of the immature stages. Unfortunately, 

 there seem to be no statistical data which would enable 

 allowance to be made for this factor. 



In the case of the first brood the eggs which I observed 

 must have been laid from i to 8 days before the date of 

 examination ; the larvae must have been deposited as eggs 

 8 to 21 days before; and the pupa: 21 to 31 days before. 

 After the hatching of the pupae of any brood, I allow for the 

 intervention of one day before the deposition of the eggs of 

 the following brood. During this time the workers are 

 engaged in cleaning and making ready the cells. It would 

 thus fall about that the cells in which the eggs of the second 

 brood were observed were formed ^2 to 40 days, those of 

 the larvae 40 to 53 days, and those of the pupae 53 to 6^ days 

 before my examination. Lastly, the eggs, larvae, and pupae 

 of the third brood occupied cells of the following ages: eggs, 

 64 to 72 days ; larvae, 72 to 85 days ; pupae, 85 to 95 days. 



Comparing these statements with the tabulated data, it is 



evident that from the presence of the oldest individuals — 



eggs, larvae, or pupae — in any cell-flat we can fix within 



definite limits the time when the first cells of the flat were 



formed. A slightly finer discrimination, based upon the 



numbers and probable state of development reached by the 



oldest members of the oldest stage, will give approximately 



the actual date on which the first cells of each flat were ready 



for the deposition of eggs — that is to say, the age of the 



cell-flat. This estimate I give in the second column following. 



Comb 6 (lowest) was between i and 8, say 6, days old. 



5 „ 21 and 3r, say 22, „ 



4 „ 21 and 31, say 30, „ 



3 „ 40 and 53, say 40, „ 



2 „ 53 and 63, say 58, 



I (uppermost) ,, 85 and 95, say 90, „ 



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