288 



SCIENCE 



[N. S. Vol. XXV. No. 634 



by systematic botanists as new species. 

 "With the exception of an occasional mon- 

 strous growth, the only mutants observed 

 have been the albino forms of red- and 

 blue-flowered species. Of these nearly 

 thirty have been found. In the lack of ex- 

 periment, no certain hybrids have been 

 found. With the exception of the oak and 

 the willow, however, no plants occur which 

 furnish any suggestion of hybridation. In 

 the region studied, accordingly, adaptation 

 is by far the most frequent method of 

 origin, mutation stands next, hybridation 

 is rare if present, while origin by varia- 

 tion, i. e., the indefinite variability of Dar- 

 win, is extremely uncertain. 



A Study of Disease Resistance in Water- 

 melons: W. A. Oeton, U. S. Department 

 of Agriculture. 



A paper presenting the results of work 

 on watermelon wilt {Neocosmospora vasin- 

 fecta var. nivea Erw. Sm.). A disease 

 widely distributed from Maryland to 

 Florida and Alabama, and occurring also 

 in Iowa, Oklahoma, California and Oregon. 

 The fungus enters through the small roots 

 and plugs the vascular system, causing the 

 sudden wilting and death of the plant. It 

 can pass its whole existence as a sapro- 

 phyte, and does remain in soil and in farm- 

 yard manure piles for ten years or more, 

 yet it is an active parasite of the water- 

 melon, attacking plants growing under 

 most favorable conditions. It is not a 

 damping-off fungus, nor a wound parasite, 

 b'ot is highly specialized as to host plants, 

 attacking only watermelons, while other 

 forms morphologically indistinguishable 

 occur in the same area as specialized para- 

 sites of cotton and cowpea. 



It is believed that this specialization ac- 

 counts for the successful production of re- 

 sistant strains, and that similar results 

 would be more difficult of attainment in 



the case of diseases caused by fungi capable 

 of attacking several hosts. 



None of more than a hundred American 

 and Russian varieties of melons tested 

 proved resistant. The inedible citron or 

 stock melon appeared to be immune, and 

 was crossed with the watermelon in the 

 hope of obtaining a resistant hybrid. A 

 resistant strain of good quality developed 

 in the third generation from this cross, and 

 has become practically fixed after three 

 years cultivation in isolated fields. 



The Problems of Vegetable Teratology: Dr. 



J. A. Harris, Missouri Botanical Garden. 

 The Significance of Latency: Dr. George 



H. Shull, Carnegie Institution. 



Paper to be published in full in Sci- 

 ence. 



The Organization of the Ecological Investi- 

 gation of the Physiological Life Histories 

 of Plants: Professor W. F. Ganong, 

 Smith College. 



The paper calls attention to the chan- 

 ging conception of ecology, which is ceasing 

 to be a search for utilities and is becoming 

 an analysis of meanings. While in broad, 

 general, or generic features, adaptation in 

 the old causative or historical sense does 

 exist, in details of structure and habit it 

 is rare if not wanting, and most so-called 

 adaptation is simply coincidence or tolera- 

 tion. In physiognomic ecology, therefore, 

 the best working hypothesis is the assump- 

 tion that the plant is an ag-gregate of phy- 

 sical needs which match or overlap the 

 physical conditions presented by the en- 

 vironment, while the completeness of the 

 overlapping determines the perfection of 

 the ' adaptation. ' The study of the physics 

 of environments has made much greater 

 progress than the study of the physical de- 

 mands of plants, and the latter now offers 

 the most important and attractive field for 

 ecological investigation. The paper then 



