RECENT EXPERIMENTS IN HYBRIDISATION. ii 



occur in the offspring (Focke, quoted by Weismann). The 

 facts above recorded as to the results of back-crossing (see 

 accounts of S. standfussi, S. risii, etc.), show that the same 

 rule holds good with hybrid SatiLrnias. 



(3) Some of the above generalisations, at present rest- 

 ing on only a few instances, can hardly be regarded as more 

 than provisional. It will be interesting to see whether the 

 further results of these experiments, which are being con- 

 tinued by their author, tend to confirm or to modify the con- 

 clusions previously reached. 



Cross-breeding between local races. Akin to the above 

 experiments are others in which local races of the same 

 species were paired. These gave results in many respects 

 analogous with the foregoing. 



1. Calliiuorpha donimula L. $ and do. var. persona 

 Hb. ?. The crossing of C. dominula S with wdiV. persona 

 ? , the latter being a local race found only in Tuscany and 

 Calabria, generally produced issue that, though very variable 

 in the perfect state, bore on the whole a closer resemblance 

 to C. do7ninula than to V2.x. persona. In one case, however, 

 a majority of the brood came nearer to the latter, and one 

 individual even went beyond the persona type. From 3 

 to 5 per cent, of the eggs were sterile. 



2. C. dominula var. persona S and C. do7ninula ?. In 

 this, the reciprocal cross, the resulting perfect insects again 

 varied between the parental types, but, on the whole, came 

 nearer to C. dominula than to the variety, though less so 

 than those of the former cross. Of the eggs, from 10 to 

 15 per cent, were sterile, from which Standfuss concludes 

 that the male of var. persona has already diverged from the 

 physiological standard of the species. 



The products of each crossing are fertile in both sexes, 

 but Standfuss is unable to say whether they have undergone 

 any diminution in fertility as compared with the parent 

 forms. 



3. Ocnogyna hemigena Grasl. c^" and O. zoraida Grasl. ? . 

 These are regarded by the author as local races of the same 

 species, the former inhabiting the Pyrenees and the latter 

 the mountains of Andalusia. The cross-product (called by 



