June 4, 1909] 



SCIENCE 



909 



have varied along morphological ones) were meas- 

 ured in a series of 500 cultures by quantitative 

 methods. The results when plotted and compared 

 showed that, on the average, certain properties 

 were notably correlated with each other, and with 

 particular habitats. A parasitic and a sapro- 

 phytic subfamily were clearly distinguished and 

 within each subfamily several genera were estab- 

 lished based on the general correlation of several 

 independent properties. Within the genera each 

 distinct modal point for a particular character 

 was given specific rank. A species is therefore 

 one of the centers about which the numerous exist- 

 ing varieties are grouped; and according to this 

 method a species can be defined, not by the de- 

 scription of an individual, but only by the statis- 

 tical study of a considerable series. 

 Effect of Age on the Venation of Leaves: H. M. 



Benedict, University of Cincinnati, Ohio. 



The size of the small areas into which the 

 leaves of dicotyls are divided by veinlets is affected 

 by the age of the plant which bears the leaves. 

 The younger the plant, the larger are these " vein 

 islets." 



That the size of these areas is not merely a 

 measure of the available nutrition is shown by 

 the fact that leaves from water-shoots which are 

 usually of larger size than normal show smaller 

 areas than smaller leaves from younger plants. 

 Young and old plants growing under the same 

 conditions of environment show the characteristic 

 difference in venation. 



As an example of the relation between age and 

 size of areas, some data from a study of Vitis 

 vulpina L. may be given. Ten mature leaves from 

 different parts of each vine were taken; pieces 

 4 by 10 mm. were cut from the same part of each. 

 These were arranged in series and photographed 

 by transmitted light and the number and size of 

 the areas calculated. Since the material was col- 

 lected where it was impossible to cut down the 

 vines the relative ages of the plants were judged 

 by the diameters of the stems. Care was taken 

 to select vines growing under the same conditions. 



Yitis vulpina L. 



Observations were made on Vlmus americana, 

 Castanea dentata, Querous alba, Q. rubra, Tilia 

 americana, Acer saocharinum, Fraxvnus americana 

 and Vitis hicolor. 



The Perennation of Cuseuta Epithymum Murr: 

 F. C. Stewaet and G. T. Feench, New York 

 Agricultural Experiment Station, Geneva, N. Y. 

 Although Kiihn proved clover dodder to be 

 perennial, by observations made in Germany forty 

 years ago, the belief is still current that the 

 species of Cuseuta are all annuals. With the 

 exception of a brief note by the senior writer 

 there is no record of any dodder in the United 

 States surviving the winter in the thread form. 

 Yet our observations indicate that Cuseuta 

 Epithymunt is frequently perennial. During the 

 past three years this species has lived over winter 

 in New York alfalfa fields, hibernating on the 

 crowns of alfalfa, red clover and certain weeds. 

 This is not accidental or occasional, but of com- 

 mon occurrence. In the writer's opinion it is the 

 chief method by which dodder is carried over 

 from one year to the next in New York alfalfa 

 fields. 



The First Generation Offspring of CEnothera lata 5 

 XO. gigaSiS: Anne M. Lutz, Carnegie Station 

 for Experimental Evolution, Cold Spring Har- 

 bor, N. Y. 



(No abstract is published, because the full paper 

 has appeared in Science.) 



The Plant Formations in Eastern Colorado, and 

 What They Indicate: H. L. Shantz, U. S. De- 

 partment of Agriculture, Washington, D. C. 

 Three chief plant formations are recognized. 

 They are discussed with respect to general appear- 

 ance, types of root systems, the water relation of 

 the soil, the influence of breaking the native sod, 

 and the changes which bring about secondary and 

 primary succession. 



'Notes on the Anatomy of Juneus (preliminary) : 

 Amon B. Plowman, Beaver, Pa. 

 In their minute anatomy the JuneaceiB are 

 strikingly similar to the more aerenchymatous 

 representatives of the Cyperaceae, such as Dulich- 

 ium, Eleoeharis and the limicolous species of 

 Scirpus. The central cylinder of the rhizome 

 shows typical amphivasal fibrovasoular bundles, 

 which are more numerous and more highly devel- 

 oped in those species of which the rhizomes are 

 short and compact. In the aerial stems showing 

 nodes, the nodal complex is similar to that in 

 DuUchium. The reproductive axis contains only 

 simple collateral bundles, arranged in the typical 

 dicotyledonous order. 



