MANUAL OF THE APIARY. 67 



THE EGG. 



This is not unlike the same in higher animals. It has its 

 yolk and its surrounding white or albumen, like the eggs of 

 all mammals, and farther, the delicate shell, which is familiar 

 in the eggs of birds and reptiles. Eggs of insects are often 

 beautiful in form and color, and not infrequently ribbed and 

 fluted as by a master-hand. The form of eggs is very various 

 —spherical, oval, cylindrical, oblong, straight and curved (Fig. 

 26, b). All insects seem to be guided by a wonderful 

 knowledge, or instinct, or intelligence, in the placing of eggs 

 on or near the peculiar food of the larva. Even though in 

 many cases such food is no part of the aliment of the imago 

 insect. The fly has the refined habits of the epicure, from 

 whose cup it daintily sips, yet its eggs are placed in the 

 horse-droppings of stable and pasture. 



Inside the egg wonderful changes soon commence, and their 

 consummation is a tiny larva. Somewhat similar changes can- 

 be easily and most profitably studied by breaking and exam- 

 ining a hen's egg each successive day of incubation. As 

 with the egg of our own species and of all higher animals, 

 so, too, the egg of insects, or the yolk, the essential part — 

 the white is only food, so to speak — soon segments or divides 

 into a great many cells, these soon unite into a membrane — 

 the blastoderm — and this is the initial animal. This blasto- 

 derm soon forms a single sack, and not a double sack, one 

 above the other, as in our own vertebrate branch. This sack, 

 looking like a miniature bag of grain, grows, by absorption, 

 becomes articulated, and by budding out is soon provided with 

 the various members. As in higher animals, these changes 

 are consequent upon heat, and usually, not always, upon the 

 incorporations within the eggs of the germ cells from the male, 

 which enter the eggs at openings called micropyles. The 

 time it takes the embryo inside the egg to develop is 

 gauged by heat, and will, therefore, vary with the season and 

 temperature, though in different species it varies from days to 

 months. The number of eggs, too, which an insect may pro- 

 duce, is subject to wide variation. Some insects produce but 

 one, two or three, while others, like the queen bee and white 

 ant, lay thousands, and in case of the ant, millions. 



