IN THE SILK-WORM MOTH. 101 



worm moths immediately on their creeping out of the cocoon, in 

 order to keep them securely in the virgin state ; they were isolated, 

 and found themselves compelled, about the 2nd to the 4th day, 

 to deposit their eggs unfecundated. Some hundreds of these 

 eggs, which were at first of a sulphur-yellow colour, gradually 

 acquired the well-known slate-grey tint, and both in this color- 

 ation and in the rest of their appearance exactly resembled the 

 eggs of fertilized silk-worm moths. As they thus showed them- 

 selves to be capable of life, they were carefully preserved by 

 Schmid through the winter, and in the spring of 1854, when 

 the mulberry hedges began to get green, they were brought out 

 of their winter dwelling-place, in order to dispose them for com- 

 plete development in a suitably warmed place. The exclusion 

 of the caterpillars took place immediately from 274 unfertilized 

 eggs laid by 24 virgin silk-worm moths ; in 270 other unfertilized 

 eggs of the same moths the caterpillars were dead before exclu- 

 sion. As regards the number of vitalizable eggs, which Schmid 

 obtained from 24 unfecundated silk-worm moths, he remarks that 

 none of these unfecundated moths laid entirely vitalizable eggs, 

 but that sometimes vitalizable, sometimes unvitalizable eggs were 

 deposited in irregular alternation one after the other by one and 

 the same individual, as immediately after four or ten or fifteen 

 vitalizable eggs, the same number or more or less of unvitalizable 

 eggs might be counted; sometimes entire masses of eggs were 

 laid, amongst which only one, two, three or four vitalizable 

 eggs were to be observed. Schmid, like myself, had also made 

 the observation that all the eggs laid by fertilized female silk- 

 worm moths are not, without exception, vitalizable, but that in 

 rare cases single unvitalizable eggs (unfecundated) occur amongst 

 the other vitalizable (fecundated) eggs. Several of the above- 

 mentioned virgin female silk-worm moths, however, laid nothing 

 but unvitalizable eggs. Of the 274 silk-worms obtained from 

 unfecundated eggs, Schmid could only keep fifteen alive, in con- 

 sequence of the extremely unfavourable conditions of tempera- 

 ture which occurred in the spring of 1854 ; he fared no better in 

 the same spring with the silk- worms obtained from fertilized eggs. 

 Of these fifteen silk-worms twelve were brought to spin up, and 

 these furnished eleven moths, amongst which there were seven 

 males and four females. Schmid allowed three of these female 



