392 LECTURE XVIII. 



The lulus terrestris hibernates from October to I\Iarch ; the female 

 is probably impregnated prior to hybernation, for her first act after 

 a,wakening from the long winter sleep is to prepare to disembarrass 

 herself of the load of impregnated ova : the act of oviposition is 

 generally over by the month of May. She previously excavates a 

 special nidamental cavity in the soil, and is careful to place the eggs 

 where no access of light, and only a certain degree of moisture, can 

 affect them. In this process she bores the soil about an inch in depth, 

 just wide enough to admit her own body, and then excavates a circu- 

 lar cavity by removing the soil, pellet by pellet, the earth being made 

 up into a little pill by mixture with her saliva ; she withdraws herself 

 backwards from her hole, bringing up the pellet, which is held between 

 her bent-down head and the first pair of legs : it is then passed back- 

 w\ards to the second pair, which transfers it to the next in succession, 

 and so onwards, until it is removed quite out of the way. When, by 

 the repetition of this manoeuvre, the egg-chamber is completed, ovi- 

 position takes place, and the entry to the chamber is carefully closed 

 by earth thoroughly moistened, so as to form a thick paste, which she 

 gently presses into the entrance, and fills up nearly to a level with 

 the surface of the soil ; thus protecting the eggs from enemies that 

 would devour them, or from the atmosphere and light which might 

 decompose them. In this operation we may perceive that the large 

 salivary glands have a function analogous to that of the silk glands'of 

 the Bombyx mori. 



In the fresh-laid e^^ the chorion is transparent, but it becomes 

 opaque, soon dries and shrivels when exposed to the air. The first 

 period of development occupies about twenty-five days, when the 

 chorion is ruptured, the egg previously augmenting in size and 

 becoming reniform. The embryo may be recognised about the 

 twelfth day, but presents no trace of segments or limbs; it is bent 

 upon itself. On the thirteenth or fourteenth day there is an indica- 

 tion of segments on the ventral aspect. On the eighteenth day the 

 shell bursts along the dorsal surface, and on the twenty-fifth day the 

 embryo protrudes, by the elastic quality of its body overcoming the 

 compression to which its growth has subjected it ; but the embryo is 

 passive and motionless, and is still connected by a n flection of an 

 amniotic covering upon the inner surface of the merabrana vitelli, 

 which connection Newport calls the " umbilicus." There is now a 

 head and seven segments, and the antennce may be seen budding from 

 the sides of the head. The internal structure of the embryo is 

 wholly cellular, with a cavity resulting from the coalescence and 

 liquefaction of certain central cells. On the third day after exclusion 

 the embryo {Jig. 154.) is passive, motionless, and still attached to the 



