I02 ENTOMOLOGICAL NEWS. [April, 



the question as to which of the above two theories is correct 

 must be left open. 



With a view to learning what, if any, light would be shed 

 upon this problem by the work of those who have experi- 

 mented with hybridization of Lepidoptera, I have examined 

 with much interest an article by M. A. Dixey in Science Pro- 

 gress ( London and Boston) for April, 1898, pp. 185 to 202, 

 entitled "Some Recent Experiments in Hybridization," which 

 contains a review and summary of the published results of ex- 

 periments of Dr. M. Standfuss, of Zurich. Also an article bj^ 

 James' William Tutt in Trans. Ent. Soc. of London, 1898, pp. 

 17-42, entitled "Some Results of Recent Experimens in Hy- 

 bridizing Tephrosia bistortata and Tephrosia crepusculariay 



Both articles deal chiefly with direct hybrids or ' ' half bloods, ' ' 

 and both writers agree in stating that hybrids are, as a rule, in- 

 fertile inter se. 



In the former article many instances of direct crossing of 

 species are given, and a few of back-crossing between hybrids 

 and one of the parent species. ' In such back-crossings where 

 the progeny were three-fourths one species and one-fourth 

 another as to their hereditary elements, no instance is cited of 

 the appearance among the progeny of any individuals exactly 

 reproducing the appearance of the species whose part in their 

 parentage was one-fourth, the admixture of blood showing 

 only in a modification of the characters of the predominant 

 parentage. 



In the latter article one instance only of back-crossing is 

 given and a similar result recorded, i. e., no example appeared 

 in which the characters of the species supplying one-fourth the 

 hereditary elements were reproduced. 



In the first mentioned article instances of crossing of Calli- 

 morpha dommula L. % with ditto var. persona Hbn. 9 are 

 given, the resulting progeny of which were " very variable in 

 the perfect state," but " bore on the whole a closer resemblance 

 to C. dommula than to var. persona.'' 



Standfuss lays down the rule that ' ' where the normal form 

 of a species is crossed with a gradually formed local race of the 

 same species the result is a series of intermediate forms. ' ' 



