LINNEAN SOCIETY OF LONDOTS". 23 



the parental forms of hybrids, in the ¥^ generation. _ I well 

 remember his telling me of the contrast between the uniformity 

 of the hybrids and the sharp division of their offspring into the 

 two parental types *. 



B. Indirect and Direct Evidence oe the Hereditary 

 Transmission or Small Variations. 



a. Persistent Variation in two Colonies of a Zygcenicl Moth on 

 E. Dartmoor. — This interesting example was observed and re- 

 corded t by Dr. E. C. L. Perkins. The colonies of Anthrocera 

 (Zyr/cena) trifoUi, ^vhich had been observed in four out of the five 

 years ending in 1914, occupied two points on the margin of a 

 pond about 1000 ft. above sea-level. They were separated in the 

 direct line by about 200 yards of water, and the intervening 

 ground along the margin was untenable by the species. Each 

 colony occupied about 15 square yards of boggy ground covered 

 with rushes, in one case intermixed with Spliagnum moss. Up 

 to 191-1 the colonies were so weak that no specimens were 

 collected, although a difference in variation was noted. In 1914, 

 however, each colony was estimated, from the number of the 

 cocoons which were prominent well up on the rushes, to contain 

 about 100 individuals. The moths from the ai^ea with Sphamvm. 

 are larger, with the red spots on the fore wing distinct or at 

 most tlie two middle ones confluent. The specimens from the 

 other area are generally of small size, and most of them have 

 " either the three apical spots connected or all are confluent, or 

 the three basal ones. In some the basal part of the hind-winjrs 

 is yellowish in daylight." The moths are sluggish and are well 

 known to cling year after year to the same small area. 



In this example the hereditary transmission of local variation 

 can hardly be doubted ; for the Sphar/num, not the food-plant of 

 the species, is scarcely likely to be called on as a JDeus ex macJiind. 



* This was the subject of liis exhibit at the Eoyal Society Soiree on 

 June 1.5, 1892. Tlie following account, printed in the programme, does not 

 explain the mode of breeding by whicli he obtained tiie results described. It 

 is nevertheless implied in these results, and as I have stated he told me 

 of it. 

 18. Exhihifed hy Mr. G. J. I?omancs, F.Ii.S. 



Living Eats and Rabbits, showing some results of experimental breeding 

 with reference to theories of hei-edity. 



The experiments prove the error of those writers who assinne that an 

 act of fertilization consists in the male and female elements intimately 

 blending together, after the manner of a merely mechanical^ mixture, so 

 that the ofispring always presents characters more or less intermediate 

 between those of its parents. In many cases this does happen, but in 

 many other cases the admixture of hereditary elements is by no means 

 intimate— those derived from the father and mother appearing to remain 

 respectively grouped together, with the results shown in the exhibit. 

 t Proc. Ent. Soc. LoncL, 1914, pp. xcv, xcvi. The specimens referred to may 

 be studied in the Hope Department, Oxford University Museum. 



