20 Allgemeine Biologie und Entwickelungslehre. 



Castle, Carpenter, Clark, Mast & Barrows present the results of extensive 

 breeding experiments on Drosophila ampelophila, designed to test primarily 

 the effects of inbreeding on fertility and variability in this species. It was 

 found that inbreeding tends to reduce fertility but any harmful effects of close 

 and constant inbreeding on productiveness may be entirely counteracted by 

 selection from families of high productiveness. If a race of low productive- 

 ness in which sterility frequently occurs is mated with a race of high pro- 

 ductiveness the Q f the first race does not have her fecundity increased by 

 the mating with the Q 1 of the second race, and conversely a Q of a highly 

 productive race does not have her fecundity diminished by mating with a Q 1 

 from a race of low productiveness. Therefore it is concluded that every Q 1 

 not actually sterile must furnish an abundance of functional spermatozoa. When 

 the Q member of a cross is from the race of high productiveness the cross- 

 bred offspring are all highly productive. If the Q member of the cross is 

 from the race of low productiveness and the tf from the highly productive 

 race the cross-bred offspring are usually, but not always, of high productive- 

 ness. There is some evidence of Mendelian segregation in the second gener- 

 ation after a cross of races of low and high productiveness. Low productive- 

 ness of the Q mav be transmitted directly through the egg from mother to 

 daughter, but only indirectly through the sperm, the character skipping a 

 generation. Inbreeding does not affect the variability in the number of teeth 

 in the sex comb of the Q?, nor the variability in size. The number of teeth 

 in the cf sex comb is closely correlated with the size of the body. 



Toyama presents the results of breeding experiments with Bombyx mori. 

 The characters studied were: color of cocoon (yellow or white), larval mark- 

 ings (striped, normal or no-markings), form of cocoons (spindle shaped or ob- 

 long), broods (uni-, di-, or multivoltine). Of these characters cocoon color and 

 larval markings "strictly follow Mendel's laws". Other characters are inherited 

 in accord with less exactly formulated laws. Both the principle of dominance 

 and of segregation were observed in these crosses. "The behavior of a char- 

 acter when crossed depends in some degree upon the characters of its ances- 

 tors". In cocoon color yellow is most dominant, next comes "flesh-color", 

 then greenish white and finally pure white, which is to be regarded as the 

 recessive. In the larval markings the striped condition is dominant over all 

 others, and the ''no-marking" condition is recessive to all others. The Japa- 

 nese normal type of coloration is intermediate. 



Jenkinson reports on an statistical study of the relation between the plane 

 of the first cleavage furrow, the sagittal plane, the plane of symmetry, and 

 the streaming meridian (i. e., gravitation symmetry plane of eggs kept in 

 "Zwangslage") in the egg of Eana. The first furrow and the sagittal plane 

 are found frequently to coincide, but there is no correlation or causal con- 

 nection between them. The symmetry of segmentation and the symmetry of 

 the embryo are independent. There is a stronger tendency for the plane of 

 symmetry of the egg and the sagittal plane of the embryo to coincide. The 

 first furrow tends to lie either in or at right angles to the plane of symmetry, 

 the former tendency being the predominant one. The reason that the first 

 furrow and the sagittal plane coincide in so many cases is that each of these 

 planes tends to lie in the plane of symmetry. The symmetry of the egg is 

 therefore fundamental, affecting the symmetry of the embryo and the symmetry 

 of segmentation. 



Davenport (*) presents extensive data on the results of cross-breeding various 

 races of Gattus domesticus. Among the general results of the work the fol- 



