Larval Dimorphism 



Bee's cell through some cranny. The Fly- 

 grub, perhaps dragging the remnants of the 

 egg behind it, must set out in quest of board 

 and lodging almost as soon as it is born. It 

 will succeed under the guidance of instinct, 

 that faculty which waits not to number the 

 days and which is as far-seeing at the moment 

 of hatching as after the trials of a busy life. 

 This primary grub does not seem to me out- 

 side the limits of possibility; I see it, if not in 

 the body, at least in its actions, as plainly as 

 though it were really under the lens. It exists, 

 if reason be not a vain and empty guide; I 

 must find it; I shall find it. Never, in the his- 

 tory of my investigations, has the logic of 

 things been more insistent; never has it di- 

 rected me with greater certainty towards a 

 magnificent biological theory. 



While vainly trying to witness the laying of 

 the eggs, I enquire, at the same time, into the 

 contents of the Mason-bee's nests, in quest of 

 the grub just issued from the egg. My own 

 harvest and that of my young shepherds, 

 whose zeal I employ in a task less difficult than 

 the first, procure me heaps of nests, enough to 

 fill baskets and baskets. These are all in- 

 spected at leisure, on my work-table, with the 

 excitement which the certainty of an approach- 

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