34 SILKWORMS. 



The sexes differ chiefly in the narrower body and more deeply 

 pectinated antennae of the male. They remain coupled often for 

 many hours. The female then deposits her eggs one by one ; 

 these, as they are extruded, are covered with a glutinous secretion 

 which causes them to adhere to the substance on which they are 

 placed. In some breeds, however, they are extruded dry, and 

 therefore do not adhere, but remain loose. In the former case 

 they are laid side by side, and not piled in heaps. Each female, 

 if in vigorous condition, may be expected to produce about 300 

 or 400 eggs, generally in batches, and the whole period of laying 

 lasts about three days. At first the eggs are bright yellow, but in 

 a few days, if they are fertile, they change to the familiar lavender 

 or slate-colour. Of course, if they are not fertile, they remain 

 yellow, and this is one way of distinguishing those eggs that will 

 produce caterpillars from those that will not. The female will 

 deposit eggs, even if she has not mated, but of course such eggs 

 are rarely of any use. Very occasionally eggs laid by virgin 

 females will mature, and produce caterpillars, the process being 

 called " parthenogenesis," but the proportion of such instances is 

 exceedingly small. For example, it is recorded that M. Jourdain 

 found that, out of about 58,000 eggs laid by unimpregnated 

 females, many passed their early stages of development within the 

 egg, thus showing that they were capable of self-development ; 

 but only twenty-nine out of the whole number produced cater- 

 pillars. 



CHAPTER III. 



THE SILKWORM ITS INTERNAL STRUCTURE. 



IN the preceding chapter we have endeavoured to gain a clear 

 idea of the external appearance of the silkworm in all its four 

 stages of egg, caterpillar or larva, chrysalis or pupa, and perfect 

 insect or imago. But if we stopped here, we should have but 

 a very imperfect knowledge of the creature's organization, for all 

 the secret processes of its life are performed inside, and if we 

 would really understand something of the way in which it lives 

 and moves, and performs its various functions, we must pursue 

 our investigations into its interior in other words, we must 

 dissect it. Packed away within the limits of its body walls there 

 are a great many different kinds of apparatus, and as these lie one 

 upon the other, they need to be separated, and to be set out 



