898 



SCIENCE 



[N. S. Vol. XXVII. No. 701 



work in whicli he had. selected out the ele- 

 mentary species produced by a self-fertilized 

 corn plant. With reference to number of 

 rows of ^ain on the cob some of the forms he 

 happened to get showed a strong tendency to 

 produce ears with ten rows and others with 

 fourteen rows. None had twelve for their 

 mode, and he had been led to the belief that 

 amongst the elementary species of corn none 

 of them, when purely homozygote, tends to 

 produce twelve rows. Dr. E. M. East, of New 

 Haven, who had done some similar work, had 

 happened to get a cross-section of the species 

 which tended strongly to produce twelve rows 

 and not ten or fourteen, which is just what 

 one would expect if the present view of ele- 

 mentary species is correct. 



Under this view, a so-called elementary 

 species is simply a completely homozygous 

 form, which necessarily reproduces itself with 

 almost absolute fidelity. The number of such 

 forms possible in a species depends on the 

 number of independent Mendelian characters 

 present, and the degree of variability of these 

 characters. The various forms under which 

 one of these characters exhibits itself may 

 represent a continuous series such as we have 

 assumed above, or the series may be broken 

 at various points, leaving gaps which are 

 bridged only in the ancestral lines of the 

 allelomorphs having a common descent, just 

 as we find the case to be with large and 

 variable groups of organisms. 



It is seen, therefore, that if Darwin's idea 

 of the manner in which evolution occurs is 

 true, then the results secured hy the hreeder 

 of so-called elementary species are a necessary 

 result of Mendelian behavior of Darwinian 

 characters. The remarkable fidelity with 

 which so-called elementary species reproduce 

 themselves is thus seen to be in entire accord 

 with the theory of gradual variation taught 

 by Darwin. 



The work of Nilsson, Shull, East and others 

 who have segregated these forms that propa- 

 gate as true to type from seed as cuttings, is 

 of great importance to biological theory, as 

 well as to the art of the breeder. Nilsson is 

 making com m ercial use, on a large scale, of 

 the principle involved. Tracy, in breeding 



seedling varieties of cassava, is doing the same 

 thing on a smaller scale, though his work 

 is only just beginning to show positive re- 

 sults. The seedlings of the cassava plant are 

 ordinarily about as variable as those of the 

 apple. Some three years ago, Professor S. M. 

 Tracy, at the request of the writer, under- 

 took to secure homozygote forms of cassava 

 at Biloxi, Miss. He now has a few varieties 

 nearly completely homozygote, and it is be- 

 lieved that within one or two seasons their 

 culture on a commercial scale will be an ac- 

 complished fact. This, it is hoped, will re- 

 juvenate an industry which had died because 

 of the uncertainty of propagating cassava 

 from cuttings. 



At least in self- fertilized species, these com- 

 pletely homozygote forms offer splendid ma- 

 terial for studying evolutionary changes, and 

 especially for studying those changes induced 

 by change of environ m ent. They should soon 

 become the starting point for some funda- 

 mentally important investigations. 



W. J. Spillman 

 U. S. Department of AGEictTLTUBE 



CURRENT NOTES ON METEOROLOOY AND 



CLIMATOLOGY 



KASSNEr'S " DAS WETTER " 



A VERY useful little book has just been 

 published by Professor Carl Kassner, observer 

 at the Eoyal Prussian Meteorological Institute 

 in Berlin, and Privatdocent at the Technische 

 Hochschule in that city ("Das Wetter, und 

 seine Bedeutung fiir das praktische Leben," 

 8vo, Leipzig, Quelle und Meyer, 1908, pp. 

 148). The plan of the volume is rather dif- 

 ferent from that of other books dealing with 

 the same subject. Its aim is to set forth, for 

 the information of the average reader: (1) 

 The historical development of weather fore- 

 casting; (2) the basis of modern weather fore- 

 casting and (3) the relations of the weather 

 to the every-day life of man. The section 

 dealing with the historical development of 

 forecasting summarizes briefly the results of 

 Hellmann's investigations into meteorological 

 folk-lore and literature. Special attention 

 may be directed to the third section, which is 



