192 . BOTANICAL GAZETTE [February 



Cytology of gigantism. — The relation between the nuclei, and particularly 

 the chromosomes, of exceptionally large individuals or varieties of a species 

 has been described in several cases. Tischler 2 * secured a giant form of 

 Phragmites communis var. Pseudodonax which reached a height more than 

 double that of the usual form. A comparison of the reduction divisions in 

 the pollen mother cells of P. communis and the var. Pseudodonax brought him 

 to the conclusion that, in this case, the gigantism arises through an increase in 

 the size of the chromosomes, without any increase in their number. Other 

 cases have been described in which the gigantism is due to an increase in the 

 number of chromosomes, as in some forms of Oenothera, Primula, and Solanum. 



The relation between chromosomes and dwarfing has received little 

 attention from botanists, but the cytology of Oenothera Lamar ckiana var. 

 nanella, as described by Gates, and some observations by zoologists, indicate 

 that the dwarfing is correlated, sometimes with a decrease in the number of 

 chromosomes, and sometimes with a diminution in their size, without any 

 change in their number.— C. J. Chamberlain. 



Ecology of fossil plants. — In a report upon some fossil plant material 

 found in the gorge of the Columbia River, in Oregon and Washington, Chaney 25 

 notes that some 80 species are represented, 75 of which are angiosperms, of 

 which 2 only are monocotyledons. A list of the genera with the number of 

 species in each includes: Ginkgo 1, Pinus 1, Smilax 1, Cyperacites 2, Populus 3. 

 Salix 3, Hicoria 2, Juglans 1, Alnus 1, Car pinus 1, Corylus 1, Castanea 1, 

 Quercus 12, Ulmus 2, Planer a 2, Magnolia 1, Laurus 2, Platanus 2, Liqui- 

 dambar 3, Crataegus 1, Sterculia 1, Rhus 1, Ilex 1, Acer 3, and Fraxinus 1. 

 From a study of this material the author concludes that the climate indicated 

 by this Eagle Creek flora appears to have been somewhat warmer and drier 

 than at present. The length of the epoch is to be placed at thousands rather 

 than at scores of years. The dominant plants point to the existence of two 

 habitats, one xerophytic and the other mesophytic. An area of upland dis- 

 sected by a valley furnishes such habitats, and at the same time meets the 

 geological requirements of the formation. — Geo. D. Fuller. 



2 -* Tischler, G., Untersuchungen uber den Riesenwuchs von Phragmites communis 

 var. Pseudodonax. Ber. Deutsch. Bot. Gesells. 36:549-558. pi. 17. 1918. 



2 * Chaney, R. W., The ecological significance of the Eagle Creek flora of the 

 Columbia River gorge. Jour. Geol. 26:577-592.^. 3. 1918. 



