132 Silkworms in India. [Vol. L 



superiority, however, of the cocoons of the European variety is so 

 obvious that many attempts have been made to introduce this form into 

 India, or to cultivate a cross between it and the native races. Except, how- 

 ever, in Kashmir, which has an almost European climate, and upon a small 

 scale in Dehra Dun and the Punjab, where the egg's are sent up into 

 the Himalayas annually for the necessary cold, the introduction of the 

 European variety has not been successful ; while crosses between it and 

 the multivoltine varieties, though at first often producing" cocoons superior 

 to multivoltine ones, rapidly deteriorate, and are considered unsatis- 

 factory 1 . It is possible that a further attempt will be made to introduce 

 the European variety into Bengal, special arrangements being made for, 

 cooling the eggs before the hatching, which it is anticipated can be 

 arranged to take place at two different times in the year, so as to give 

 two crops, as has already been done in Italy 2 . It remains, however, to 

 be seen to what extent this attempt will prove successful. 



Silkworms can be raised upon all kinds of mulberry. For adoption 

 in India Duthie recommends the variety Morus multicaulis as most 



1 See Bashford's Experiments (Geoghegan's Account of Silk in India ; 1872, p. 21) in 

 crossing French, Italian, and China annuals with Madrassi and Uesi multi' 7 oltines. The 

 results, tbough promising at first, were not considered satisfactory, as the stock rapidly 

 deteriorated and geuerally reverted to inferior annuals. See also an account of a similar 

 experiment carried out in the Indian Museum {Indian Museum Notes, Vol. I, No. 2, p. 123). 



2 Rondot, in his L'Art de la Sole, writes that Duseigneur mentions two rearings made 

 in one year near to Sorreute in the province of Naples. The eggs belonged to an annual 

 variety and were preserved in some cold caves. One part, put to hatch at the usual time, 

 gave the first crop ; the rest remaining subject to the cold, and nut to hatch later on gave 

 a second crop which was smaller than the first. 



The conditions which regulate the hatching of eggs of the annual variety are as 

 follows, according to Du Claux (see Mukkarji's Notes, published by the Government of 

 Bengal, 1888): 



WheD the eggs are first laid they breathe with activity, the oxidization causing them 

 to change in colour from yellow to purple. At this stage the forced suspension of vitality 

 by the application of cold is hurtful, but after a period of three weeks or a month, the 

 eggs enter into a state of rest, and can then be subjected without harm to the cold which 

 is necessary for starting the further development of the embryo. The temperature required 

 for this refrigeration is about 32° to 40° Fahrenheit. In the case of eggs refrigerated soon 

 after being laid, a two months' sojourn in the refrigerator is necessary ; a shorter period, 

 however, sufficing for eggs that are already several months old when subjected to the 

 action of cold. After coming out of the refrigerator a period of six weeks or two months 

 of a low but gradually rising temperature is required for the healthy development of the 

 eggs, before they are hatched out by the action of a temperature of about 75° Fahrenheit. 

 When once the eggs have been refrigerated the development of the embryo proceeds 

 regularly, and any attempt to retard the hatching is deleterious: the time passed in the egg 

 stage can therefore be increased or diminished only by increasing or diminishing the 

 period that elapses before refrigeration. Du Claux succeeded in getting eggs to hatch 

 out healthily within about 145 days of being laid, instead of the usual ten months ; this he 

 did by taking eggs about 20 days old and exposing them to the action of cold for two 

 months, and then to a low but gradually rising temperature for six weeks; at the end of 



