Chap. VIII. THEIR DIFFERENCES. 301 



been the close attention which has long been applied in many 

 countries to every promising variation. The care taken in 

 Europe in the selection of the best cocoons and moths for 

 breeding is notorious, 66 and the production of eggs is followed 

 as a distinct trade in parts of France. I have made inquiries 

 through Dr. Falconer, and am assured that in India the natives 

 are equally careful in the process of selection. In China the pro- 

 duction of eggs is confined to certain favourable districts, and the 

 raisers are precluded by law from producing silk, so that their 

 whole attention may be necessarily given up to this one object. 67 



The following details on the differences between the several breeds are 

 taken, when not stated to the contrary, from M. Eobinet's excellent work, 68; 

 which bears every sign of care and large experience. The eggs in the 

 different races vary in colour, in shape (being round, elliptic, or oval), 

 and in size. The eggs laid in June in the south of France, and in July 

 in the central provinces, do not hatch until the following spring; and it 

 is in vain, says M. Eobinet, to expose them to a temperature gradually 

 raised, in order that the caterpillar may be quickly developed. Yet occa- 

 sionally, without any known cause, batches of eggs are produced, which 

 immediately begin to undergo the proper changes, and are hatched in from 

 twenty to thirty days. From these and some other analogous facts it may 

 be concluded that the Trevoltini silkworms of Italy, of which the cater- 

 pillars are hatched in from fifteen to twenty days, do not necessarily form, 

 as has been maintained, a distinct species. Although the breeds which 

 live in temperate countries produce eggs which cannot be immediately 

 hatched by artificial heat, yet when they are removed to and reared in a 

 hot country they gradually acquire the character of quick development, 

 as in the Trevoltini races. 69 



Caterpillars.— These vary greatly in size and colour. The skin is gene- 

 rally white, sometimes mottled with black or grey, and occasionally quite 

 black. The colour, however, as M. Eobinet asserts, is not constant, even 

 in perfectly pure breeds ; except in the race tigree, so called from being 

 marked with transverse black stripes. As the general colour of the cater- 

 pillar is not correlated with that of the silk/ this character is disregarded 



66 See, for instance, M. A. de Quatre- the moths thus raised produced eggs 



fages 'Etudes sur les Maladies actu- which were even worse in this respect. 



elles du Ver a Sole,' 1859, p. 101. Some were hatched in ten days, and 



7 My authorities for these statements others not until after the lapse of 



will be given m the chapter on Selec- many months. No doubt a regular 



™ < nr , , * m , earl y character would ultimately have 



• ■ Manuel de lEducateur de Vers been acquired. See review in <Athe- 



a k° ie > *f*°- namm,' 1844, p. 329, of J. Jarves' 



- Eobmet, idem pp. 12, 318. I may < Scenes in the Sandwich Islands.' 



add that he eggs of N. American silk- 70 . The Art of rea . snk . worms/ 



worms taken to the Sandwich Islands translated from Count Dandolo, 1825, 



were very irregularly developed ; and p. 23. 



