Januaet 29, 1915] 



SCIENCE 



177 



gories of vegetation. By calculating the percent- 

 ages of tlie growth-foims in the flora of difEerent 

 regions, we get the record of the vegetative re- 

 sponse to climate, with all its infinite variation. 

 Applying the method for the flora of the vicinity 

 of New York, where, excluding weeds, ferns and 

 parasites, there are 1,907 wild species, the per- 

 centages of growth-forms are as follows: 



Megaphanerophytes 52 per cent. 



Mesaphanerophytes 4.03 per cent. 



Microphanerophytes 7.18 per cent. 



Nanophanerophytes 3.51 per cent. 



Chamaephytes 5.29 per cent. 



Hemioryptophytes 33.29 per cent. 



Geophytes 20.23 per cent. 



Helophytes and Hydrophytes 11. 74 per cent. 



Therophytea 13 per cent. 



The percentage of geophytes is larger than that 

 for any region yet studied, leading to the conclu- 

 sion that the climate near New York is of such a 

 nature that the development of geophytes is espe- 

 cially favored. Studies were also made on the 

 northern and southern elements of the flora of 

 New York, and on the high-mountain species of 

 the region; the percentage of growth-forms being 

 given for each of these groups, and for difEerent 

 regions of the earth's surface to compare with 

 the local flora near New York. 



The Effect of Breeding and Selection upon the 



Percentage of Total Alkaloids in some Species 



and Hyirids of the Genus Datura: Feed A. 



Miller and J. W. Meadee. 



Through selection and hybridization an attempt 



has been made to develop a strain of stramonium 



which would show an increased percentage of 



alkaloids over that of the commercial stramonium 



leaf used for medicinal purposes. All selected 



plants have been carefully inbred. The alkaloidal 



assays have been made upon samples of air-dried 



leaves from individual plants. The species so far 



used are Datura stramonium L., D. tatula L. and 



D. ferox It. 



On the Nature of Mutations: E. Ruggles Gates. 



Hybrids of (Enothera iiennis Linnaeus and O. 



franciscana Bartlett in the First and Second 



Generations: Bradley Moore Davis. 



Among the contrasting characters of the parent 



species is one especially well adapted to a genet- 



ical study. In CEnothera biennis the papillae at 



the base of long hairs follow the color of the 



green stems; in 0. franciscana the papillae are 



bright red. Hybrids of reciprocal crosses all 



have red papillEe, the color thus appearing as. a 

 simple dominant. Cultures of the hybrids in the 

 second generation totaled 1,806 plants from sow- 

 ings of 3,554 seed-like structures; 1,679 rosettes 

 sent up shoots during the season, and on every one 

 of these plants the papilla were bright red. 

 There was thus a failure of the color character to 

 segregate in the T, in cultures containing 1,679 

 plants, and its behavior was not what might have 

 been expected from/ Mendelian experience. How- 

 ever, it should be noted that of the 3,554 seed-like 

 structures sown 1,748 failed to germinate, although 

 seed pans were kept for 8-10 weeks. Also that 

 127 plants either died during the season or else, 

 remaining as rosettes, failed to send up shoots 

 upon which observations could be made. It is 

 thus possible that the absence of a class of green- 

 stemmed reeessives may be associated with this 

 high degree of seed sterility, the cause of which 

 is as yet not known, or with the failure of some 

 plants to mature. 



In previous papers mention has been made of 

 the fact that the -Pi hybrids of the cross fran- 

 ciscana X biennis in many characters were simi- 

 lar to (Enothera Lamarckiana, differing from this 

 plant only in relatively small plus or minus ex- 

 pressions of these characters. The second genera- 

 tion of this cross, as was to have been expected, 

 presented a wide range of forms, and among these 

 were a number of plants with combinations of 

 characters that appear to have fulfilled in essen- 

 tials the requirements of a synthetic LamarcTciana- 

 like hybrid. Further generations from these se- 

 lected plants will be grown to test their further 

 range of variation. 



A detailed account of the above-considered cul- 

 tures wiU later be published. 



Inheritance of Certain Seed Characters in Corn: 



E. A. Harper. 



The various pigmentations of the integument, 

 aleurone layer and endosperm are metidentical 

 characters in Detto's sense, that is, the same in 

 the cells as they are in the tissues or the kernel, 

 as a whole. The pattern in the case of streaked 

 or mottled grains is a character of the tissue, as a 

 whole. The form of the dent kernels; is a char- 

 acter of the kernel, as a whole, due to the nature 

 and distribution of the starch and other elements 

 in the tissues. The wrinkled form of the kernels 

 of sweet corn is more nearly identical with the 

 shrinkage of the individual cells of the endo- 

 sperm. By crossing, intermediates may be ob- 

 tained between any two such contrasting chaxae- 



