No. 1, July, 1920] ECOLOGY, PLANT GEOGRAPHY 33 



dishes containing glycerine-soaked filter papers on board 2 light-ships stationed ■''» and 5.5 

 miles from the shore in the Gulf of Bothnia, Sweden. From May 16 to June 26, 1918, the total 

 number of grains collected on a square millimeter of Burface was 16.2 a1 •'; miles and 8.8 a1 5 5 

 miles. Spruce (Picea exceha) and birch I Betula 8pp.) were almost equally represented, with 

 considerably less of pine (Pinua Bylvestris), and very feu of all other specie Other inv< 

 gat ions and observat ions are cited to show thai pollen grains may be carr ed by wind .-is much 

 as 70 to 90 miles. This factor tends to counteract the development of local climal IC form- or 

 races of trees. It operates most effectively in the case of species such as the spruce which 

 commonly open the pistillate llowers in advance of the Btaminate, and leasl effectively in 

 species such as the pine in which this relation is reversed. This factor is suggested as ac- 

 counting for the greater prevalence of "climatic races" in pine than in spruce. It is also 

 pointed out thai in plant breeding experiments it is of great importance to determine whether 

 the individuals from which seed is collected blossomed earlier or later than their associates. 

 Another field which is touched upon is that of paleobotany, in so far as the fossil flora of a 

 region is determined by the occurrence of pollen grains, it being pointed out that the presence 

 of fossil pollen grains of a given species is by no means certain evidence that the species 

 occurred in the immediate locality, since the pollen grains may have been carried from a 

 remote region. [See also Bot. Absts. 4, Entry 253.]— G. A. Pearson. 



233. Hodson, Elmer R. [Rev. of Hanson, Herbert C, Leaf structure as related to 

 environment. Amer. Jour. Bot. 4: 533-560. 1917.] Jour. Forestry 17: 1S6-188. 1919. — 

 Work differs from usual methods in that the environmental factors were measured. Leaves 

 of the interior of the crown were compared with those in the periphery on the south side and 

 those on the outside had much thicker leaves than those on the inside, the difference being 

 greater than the differences between mesophytic and xerophytic leaves. Evaporation was 

 from 1.5 to 2.3 times as great an the periphery as in the crown, humidity was from 1 to 6 per 

 cent higher in the crown, while the temperature was from to one two degrees low 7 er in the 

 crown than in the periphery. Leaves on the outside of the crown lose more water per unit 

 area than center leaves, while they were in general smaller, deeper lobed and had a lower 

 water content. [See Bot. Absts. 1, Entries 1326, 1328.]— #. N. Munns. 



234. Howe, Inez Addie. November flowers in northern Vermont. Rhodora 21: 170. 

 1919. — A list of 44 species of plants which were found flowering in the neighborhood of the 

 Fairbanks Museum at St. Johnsbury, Vermont, and were exhibited on the flower table at 

 the museum between the first and the twenty-second of November. These were all cases of 

 either second or continuous blooming resulting from the unusually wet, mild weather of 

 October and November 1918. — James P. Poole. 



235. Hutchinson, J. The rain tree of Hierro, Canary Islands [Oreodaphne foetens]. 

 Kew Bull. Misc. Inf. [London] 1919:153-164. 8 fig. 1919.— The peculiar features of this tree 

 were krownto the Romans who considered this island tobethe western boundary of the world. 

 This tree, like other species of Lauraceae, is shown to be an important agent in the condensation 

 of moisture from the clouds. It is suggested that the judicious planting of such trees might so 

 far increase the soil moisture as to make possible a considerable extension of banana culture 

 in the Canaries. A critical and historical study is given of the efficiency of this tree in the 

 condensation of water. — E. M. Wilcox. 



236. Jektll, Gertrude. Pollination of Viscum album. Jour. Botany 57: 286. 1919. — 

 A brief record is given of an experiment in pollinating this plant. It is claimed that the 

 presence of fertilized fruit inside of the mesh inclosure supports the results of experiments 

 by Dom Ethelbert Horne wdiich seemed to show fertilization is not necessarily due to bees 

 and flies, as was claimed by Koelreuter, Kirschner and Loew. — K. M. Wicgand. 



237. King, C. M., G. J. Ringland, and Hemenway Martha. Blooming time of Iowa 

 plants 1918.— Rept. Iowa State Hortic. Soc. 53: 226-231. 191S— Paper gives the blooming 

 time of the common plants of Iowa at three different places; Ames, Boone and Lansing, with 

 additional notes on the blooming of a few plants at Davenport and Council Bluffs, Kansas 

 City, Missouri, and Manhattan, Kansas; also weather notes. — L. H. Pammel. 



BOTANICAL ABSTRACT8, VOL. IV, NO. 1 



