116 CARNEGIE INSTITUTION OF WASHINGTON. 



"In the jimson weed (Datura) it has been possible to further test the 

 inheritance of the 'globe' mutant, since the mutant can be recognized in 

 the seed-pans. Over 5,000 seedlings have been grown this winter in the 

 test, about equally distributed between selfs, globes X normals, and normals 

 X globes. When the globes are selfed and the globes as females are crossed 

 with normals about the same results are obtained in the offspring, i e., approx- 

 imately 3 normals to 1 globe; while normals crossed with globes as male 

 parents throw about 38 normals to 1 globe. The mutant complex therefore 

 seems to be but slightly transmitted through the male parent. It is trans- 

 mitted through the female parent either when selfed or when crossed with a 

 normal, but appears in only about a quarter of the offspring. The mutant 

 has been selfed for five generations, but as yet it seems impossible to obtain 

 a pure race of globes. The mutants 'cocklebur,' 'poinsettia,' and others seem 

 to be inherited in much the same manner, although extensive tests have not 

 been made of other mutants than the globe. 



"Last year a 'quercina' disease of the jimson weed was reported which 

 causes a laceration of the leaves, splitting of lobes of the corolla, and a sup- 

 pression of spines on the capsules. This disease was found to be transmitted 

 by grafting, but not by contact nor by inoculation. Another disease some- 

 what similar in its effects has been discovered. It causes a more pronounced 

 malformation of the leaves (often reducing them to mere midribs) , induces a 

 suppression of spines on the capsules and the production of distorted acces- 

 sory carpels in the flowers. It is readily propagated by contact of diseased 

 leaves with normal plants. It also differs from the 'quercina' disease in that 

 it is not carried by the seed. 



"Several years ago at Storrs, Connecticut, a study was begun upon the 

 inheritance of the weeping habit of a number of trees. Last season a single 

 tree from a cross between Tee's weeping mulberry and the common white 

 mulberry came into flower and was back-crossed with the weeping variety. 

 Some hundred seedlings from this cross are now growing in the garden and, 

 while definite counts have not been made as yet, the erect individuals and 

 those spreading prostrate like a vine over the ground are approximately in 

 equal numbers. From the results of this back-cross the weeping habit in the 

 mulberry would seem to be a simple Mendelian recessive. Seedlings from 

 inter se crosses made between F2 plants this spring are now growing in the 

 greenhouse and may be expected to show 3:1 ratios in habit characters by 

 next summer. 



"In cooperation with Dr. Harris and with the Poultry Department of the 

 Storrs Agricultural Experiment Station, we have published a bulletin on 

 pigmentation and other criteria for the selection of laying hens, which em- 

 bodies our results already reported, together with new data. Our results seem 

 to be proving of practical value to poultrymen in their attempt to cull out the 

 unproductive birds from their flocks and thus to reduce their feed bills." 



Dr. J. Arthur Harris has continued his work in various lines and 

 reports as follows: 



"Investigations of osmotic concentration of vegetable saps. — These studies 

 have been continued along lines indicated in previous reports. A memoir 

 on the plants of the Jamaican coastal deserts has been published in coopera- 

 tion with Mr. John V. Lawrence. The results show excellent agreement with 

 conclusions already drawn from investigations of the Arizona deserts. The 

 results of a first study of desert Loranthacese parasitic on various hosts have 

 also appeared. The desert Loranthacese, like the desert host-trees, show a 

 far higher osmotic concentration than those studied in the Jamaican montane 



