120 CARNEGIE INSTITUTION OF WASHINGTON. 



carried the defect in their germ-cells, but had never been able to reveal 

 it up to that time in their progeny because all of the female germ-cells 

 previously fertilized bj'' their pollen had carried the determiner for 

 broad-leaf. The fact that an hermaphrodite crossed with a hetero- 

 zygous female exhibited this defect in its offspring completely confirms 

 Dr. Shull's conclusion that his hermaphrodite mutants in this species 

 were originated through a mutational change in the males. This 

 important experiment supports the view, suggested long ago by de^'ries, 

 that many heterozygous individuals may carry a defect in their germ- 

 plasm, even as a racial character, and this character ma}'' never express 

 itself in the progeny because it has never got into the geiTn-cells of the 

 opposite sex. In this paper a much-needed revision of sex-formulse is 

 undertaken which, it is hoped, may simplify and standardize current 

 usage. 



VARIATION. 



The problem of variation of organisms still remains unanalyzed and 

 little progress had been made in its treatment. At this Station this 

 summer (1914) we have made a systematic search for striking variations 

 in the field, we have studied the relation of variations in a plant to their 

 position on the plant, and we have compared the chemical composition 

 of varying organs or plants to learn how far the chemical differences 

 that accompany morphological variations can be detected. Finally, 

 we have made a beginning on the task of inducing hereditary variations 

 at will — that is, altering the germ-plasm. 



Mutations in Nature, H. H. M. Bowman. 



During July and August 1914, Mr. Howard H. M. Bowman was 

 assigned to the work of looking for striking and probably inheritable 

 variations in plants near the Laboratory, with the aim of locating material 

 that might be used for future studies in variation. In this search he 

 was successful, since he recorded such variations, mutations, and aber- 

 rations in 66 species. He also recorded the condition of each leaflet 

 for 393 seedling Fraxinus (ash) of known pedigree from ascidiate 

 (pitcher-leafed) and non-ascidiate ancestry. The results will be used 

 in Dr. Shull's study of this remarkable mutation. 



Periodicity in Abnormality in the Passion Flower, J. A. Harris. 



In Passiflora (the passion flower) the fruit shows a great number of 

 abnormalities, mostly proliferation and allied phenomena. A com- 

 parison of the number of abnormalities in plants grown in normal soil 

 and in soil to which a considerable proportion of bone-meal had been 

 added showed no difference in the proportion of abnormal fruits, but 

 established the fact that the proportion of abnormalities in the fruits 



