20 



tunately, however, when we look further into details, we find that this 

 inference was entirely a false one, there "being in point of fact no real 

 improvement in the worm at all, except that it was healthier when fed upon 

 the more solid leaf of M. Sinensis than upon those of the thin watery leaf 

 of M. cucullata ; moreover, there was no improvement upon the worms of 

 the first year, for these died off in such vast numbers as to render a fresh 

 importation from Calcutta necessary, so that it was only annually com- 

 mencing the same experiment de novo. To establish an improvement in 

 the worm required that the worms of the first year should have perpetuated 

 themselves, and then gone on annually improving, and this they did not do ; 

 in short, the experiment never advanced at all, but annually recommenced 

 with the importation of fresh ones from Calcutta. The fact that the worms 

 annually imported throve better on M. Sinensis than the first batch had done 

 on M. cucullata is a propos to nothing, as it only shows that the worms 

 thrive better upon good than upon bad food. Besides which it appears that 

 the alleged improvement was entirely the exception, the majority of worms 

 dying off, and leaving a few good ones to prove the rule that the climate was 

 inimical to the species. As to B. mori and B. textor, they are acknowledged 

 to have been a failure. 



In conclusion then, permit me to say one more word on the crossing of 

 species. Darwin has stated that if a plant's own pollen be brought on a 

 brush it will invariably prove prepotent over that of a foreign species, that 

 is to say, that nature rejects all crossing so long as a plant's own pollen is 

 available. 



Now if we apply this natural law to the silkworm, it will at once show 

 why the progeny of two different species when crossed invariably, sooner 

 or later, revert to their original state, or more commonly to that of the 

 strongest species. "We cross t.fortunatus upon B, mori; the moths produced 

 have, so to speak, the blood of both species ; but when they couple there is 

 a straggle for the mastery between the two, each striving to cast out the 

 other, and the blood of the stronger species will prove prepotent over that of 

 the weaker, and consequently, unless the latter be recrossed by its own 

 species, it must by the law of nature revert to an annual. Here the stronger 

 blood of B. mori in the male moth meeting with an equal portion of the 

 same blood in the female proves prepotent over the two parts of the blcod 

 of the weaker B. fortunatus, and casts it out by reverting to annuals. 



These two species at Musaooree, when the crossing is judiciously kept up, 

 produce a very excellent silk of a golden colour, the cocoon being much 

 larger than that of B. fortunatus of Bengal, but when once the crossing 

 ceases B mori invariably reappears. But it is time to stop, for methinks I 

 hear you cry " Ohe,jam satis." 



THE HON. SECBETAEY OP THE ACCLIMATISATION SOCIETY OP 

 NEW SOUTH WALES to His EXCELLENCY THE VICEBOY OP 

 INDIA, SIMLA. 



Acclimatisation Society of New South Wales, 



Sydney, 24 February, 1870. 

 MY LOBD, 



I have the honor to acknowledge receipt of despatches 

 from your Excellency, No. 3749, dated 13 August, No. 555, 

 22 September, and 4771, 20 October, and to express the warm 

 thanks of the Council of this Society for the pains taken in virtue 

 of your Excellency's instructions to comply with our desire for 

 silkworms' eggs and seeds. 



