THE TECHNOLOGIST. [Dec. 1, 1864. 



222 ON THE REVERSION AND 



sider the Bengal monthly worms to be. Bat to extol in general terms 

 one species above another, and endeavour, on wholly insufficient and 

 often purely theoretical data, to persuade people that it is the best 

 adapted for the nourishment of the silkworm, — the species of worm, 

 moreover, not being specified, — is, in my opinion, the surest way of 

 propagating pure sophistry and of insuring the failure of speculations in 

 other districts, which, from the nature of their climates, require both a 

 different diet and a different mode of treatment. 



There is, moreover, yet another point to be considered, for although 

 certain trees, such as M. multicaulis and M. cucullata, may thrive well 

 enough in the Punjab and the Gangetic provinces, yet it is more than 

 doubtful whether the Cashmere worm will thrive upon them ; for while 

 the trees delight in and are adapted to a warm lowland temperature, the 

 insect, whose cultivation is becoming fashionable in the upper provinces, 

 is from the northern mountainous tracts of China, situated between 32° 

 and 34° of north latitude, whereas in our Himalayan regions frost and 

 snow are the accompaniments of winter. The cultivator should remem- 

 ber that a northern insect requires a northern tree, and the northern 

 tree requires a northern climate, and that he himself requires a certain 

 amount of knowledge and the exercise of common sense. 



Trees producing leaves of extreme thinness, like those of M. multi- 

 caulis and M. cucullata, are far from desirable on account of their contain- 

 ing but little nourishment, and necessitating a larger and more frequent 

 supply. A good and healthy leaf should contain the four ingredients 

 of fibre, water, saccharine, and resinous matter ; the first two go directly 

 to the nourishment and growth of the worm, while from the latter two 

 is secreted the supply of gum which eventually furnishes the silk. 

 Where the two former only are found, or where they are greatly in 

 excess, as is sometimes the case, the -worm -will grow and attain to a 

 goodly size, but will produce little, or perhaps no, silk. In breaking off 

 a good healthy leaf, a drop or tw T o of thick milky viscous juice should 

 exude from the stalk, and in this resides the silk-producing matter ; 

 the Morus sinensis and all the thick-leaved trees possess this is in far 

 greater quantity than either M. cucullata or M. multicaulis, and indeed 

 from the latter species, when grown in a cold climate, it is almost absent, 

 being thin and watery. 



Yet after all, it has long since been laid down as an ascertained fact, 

 that however much the quantity of silk may be dependent upon the 

 presence of this juice, the quality is far less dependent upon the good 

 properties of the leaf than upon the temperature in which the worms 

 have been reared ; so that wdiere this is higher than the constitution of 

 the insect is fitted to endure, no matter how well it may have been fed, 

 the yield will always be inferior to that produced in a more genial 

 temperature ; and that the Bomhyx mori of Cashmere is greatly influ- 

 enced by the heat of the Punjab, is proved beyond all contradiction by 

 M. Perrottet's observation, in epistold,. that eggs deposited there and 



