102 PARTHENOGENESIS 



moths to lay eggs without fertilization, but all the eggs deposited by 

 these three virgin female silk-worm moths remained light yellow, 

 and soon shrivelled, so that they had not been vitalizable. The 

 fourth of these females paired with one of the seven males which 

 had been reared from unfertilized eggs ; the eggs laid by this 

 female after the act of copulation were all, with the exception of 

 sixteen, vitalizable, and furnished very fine silk-worms in the year 

 1855. Of the six other male silk-worm moths, two were employed 

 to copulate with other ordinary females ; these latter also laid 

 throughout vitalizable eggs, from which very fine silk- worms were 

 produced. In the year 1854 Schmid again selected twenty-four 

 female cocoons of silk-worms, which were all separated singly 

 and strictly inspected. From these, twenty-three females and 

 one male escaped; the latter was removed immediately after his 

 exclusion. The twenty- three females deposited their eggs more 

 or less irregularly in their solitary cells, and amongst these there 

 were only twenty-one vitalizable eggs, the whole of w r hich were 

 laid by four of these moths ; all the rest of the eggs had for the 

 most part remained pale yellow, or had become reddish-brown, 

 and then shrivelled. Unfortunately, in the following year, 1855, 

 the breeding of the caterpillars from these twenty-one eggs was 

 unsuccessful ; the twenty -one caterpillars had been perfectly de- 

 veloped in them, but their exclusion must have been retarded 

 on account of want of nourishment, by which they died within 

 the egg-shell. In the year 1855, Schmid selected eight female 

 cocoons, which w-ere separated and watched with equal care and 

 anxiety. They furnished eight female moths, of which seven 

 individuals deposited their whole store of eggs in the virgin 

 state, whilst the eighth female, notwithstanding the greatest 

 exertion, could not deposit even a single egg. Schmid sent me 

 the entire harvest of eggs from these moths upon seven strips of 

 paper ; there may have been about 3600 eggs ; each of the strips 

 of paper contained about 512 eggs, which these moths had 

 attached during deposition. On the first strip all the eggs were 

 still tense, and furnished with the flat central depression ; forty 

 of them had retained their light yellow colour, five had ac- 

 quired a slate-grey colour, and all the rest appeared reddish- 

 brown. The second strip of paper bore eighteen bright yellow 

 and seven slate-grey eggs ; all the rest were of a reddish-brown 



