28 ECOLOGY, PLANT GEOGRAPHY [Bot. Absts., Vol. IV, 



198. Raunkiaer, C. Uber das biologische Normalspektrum. [Normal biological spec- 

 trum.] Kgl. Dansk. Vidensk. Selskab. Biol. Meddel. I 1 : 17 p. 1918. — The author suggests 

 certain changes for the simplification of his life-form system of classification and adds more 

 data to the application of his normal biological spectrum. Analyzing floras from such widely 

 different regions as Denmark, Spitzbergen, Death Valley (Calif.), Georgia, Seychelles, and 

 Alaska he finds that not all of his life-forms are essential to the characterization of their phyto- 

 geographic climates. For the purpose of such characterization he finally reduces his ten 

 life-forms to four, viz., phanerophytes, chamaephytes, hypogeal plants and therophytes. 

 The recalculation of a normal spectrum upon the basis of many more species than originally 

 used for that purpose proves that the earlier calculation was quite accurate. A study of the 

 great taxonomic groups of plants shows that the calculated and experimental results agree 

 and that while the Gymnospermae and Choripetalae are essentially phanerophytic, the Mono- 

 cotyledonae are characteristically hemicryptophytic and cryptophytic while the Gamo- 

 petalae possess a majority of hemicryptophytes. [See also Bot. Absts. 4, Entry 301.] — H. de 

 Forest and Geo. D. Fuller. 



199. Reed, William Gardner. Frost and the growing season. Atlas of Amer. Agric. 

 Part II, Sect. 1. 11 p. 33 fig. 1918. — A series of shaded maps of the United States showing: 

 {1) the average dates of the last killing frost in spring for the different portions of the country; 

 (2) number of times in the given period when the first killing frost of spring was 10 days or 

 more later than the average date; (3) average dates of first killing frosts in fall; (4) number 

 of times in the given period when the first killing frost in fall was 10 days or more earlier 

 than the average date; (5) dates on which the chance of killing frost in spring falls to 10 per 

 cent; (6) dates on which the chance of killing frost in fall rises to 10 per cent; (7) number 

 of times in the period when the season without killing frost was 15 days or more shorter than 

 the average; (8) average number of days without killing frost; (9) available growing seasons 

 in four-fifths of the years. Other interesting data concerning the time of occurrence of kill- 

 ing frost in specific years and places, are mapped and charted. Most of the data is obtained 

 from frost records extending over a period of twenty years (1895-1914). Full rev. by Ward 

 in Geog. Rev. 7: 339-344. 1919.— P. D. Slrausbaugh. 



200. Reidy, Margaret M. Ecology. School Sci. Math. 19: 131-134. Feb., 1919.— 

 A paper dealing with the pedagogical aspects of ecology. — See Bot. Absts. 2, Entry 894. 



201. Roig, Juan T. Las maderas de Isla de Pinos. [Kinds of wood on the Isle of Pines.] 

 Revist. Agric. Com. y Trab. 2 : 498-500. 1 fig. 1919. — In the course of a collecting trip through 

 the Isle of Pines there were collected 19 samples of wood not in their collection, 150 herbarium 

 specimens and a considerable number of seeds of forest plants. Note was also made of a 

 hundred common names not at present in catalogues and dictionaries. In general the species 

 ■of trees found were the same as those in certain similar sections of Cuba. In the trip not a 

 single marabou plant was seen. The mallows, Urena lobata and U. sinuata, were especially 

 abundant about New Gerona. Attention is called to the fact that "sabina de costa" is nearly 

 extinct both in Cuba and the Isle of Pines. — F. M. Blodgett. 



202. Rowlee, W. W. Relation of marl ponds and peat bogs. Mem. Brooklyn Bot. Gard. 

 1 : 410-414. 3 fig. 191S. — Two types of filled in lakes and ponds occur in western New York: 

 the peat bog and the marl pond. These differ in respect to the character of the water, the 

 flora of the water, and the manner of filling. Finding many of the peat bogs underlain with 

 marl, the author raises the question as to the possibility of such bogs having previously con- 

 tained alkaline water which subsequently became non-alkaline. As most of the marl ponds 

 occur in the region near the limestone belt of central New York, and the peat bogs with the 

 greatest amounts of marl under them also occur near this same limestone belt, the author 

 tli inks that the above mentioned change has taken place. To quote his words, "The ponds 



e artesian pools fed by these springs and as the character of the water changed, there 

 was, if our theory is correct, a corresponding change in the flora." Chara, a lime-loving 

 plant, removes free lime from the water; rain washes out the lime from the soil, so that even- 

 tually the lime content of the pond water would be decreased, and conditions would arise favor- 

 ing the development of an oxylophyte flora. — P. D. Slrausbaugh. 



