RECENT EXPERIMENTS IN HYBRIDISATION. 



IT has long been recognised that the facts of hybridisation 

 have an important bearing on many subjects of biolo- 

 gical interest. The question of the infertility of crosses was 

 very carefully investigated by Darwin, and since his time 

 has been more than once discussed afresh ; while the struc- 

 tural and other characters presented by hybrid offspring 

 are of undoubted weight in reference to the problem of 

 heredity. 



For some years past Dr. M. Standfuss, of Zurich, has 

 been experimenting on a large scale in the production of 

 insect hybrids. The results of these experiments, some of 

 which confirm previous views, while others appear to sug- 

 gest conclusions not hitherto reached, have now been collec- 

 ted by their author in his Handbuch der pal'darktischen 

 Gross-Schmetterlinge, published at Jena in 1896. Many of 

 the data thus made available derive especial value from the 

 fact that they are expressed numerically, and the whole 

 series forms a noteworthy contribution to our knowledge of 

 the subject. It is proposed to give here a short account of 

 these experiments, with their results, for the benefit of those 

 readers to whom the original records may be difficult of 

 access. 1 



The authorprefaces his account with a list of fertile and 

 infertile pairings between different species of macrolepi- 

 doptera that have been observed by himself and others, 

 both under natural conditions and in captivity. Details are 

 first given of twenty-four cases of pairing between Bombyx 

 neustria L. S and B franconica Esp. ? . The results 

 showed every transition between complete absence of issue 

 and the deposition of eggs normal in numbers and fertility. 

 Failure was in some instances plainly due to inadaptability 

 of the genital apparatus. On this series of pairings Stand- 



1 Several of Dr. Standfuss's specimens have lately been exhibited in 

 London, at the rooms of the Royal Society, Burlington House and at the 

 Natural History Museum, South Kensington. 



