FIELD CROPS. 29 



Investigations on the later resting stages of bulbs, P. Cheistensen ( Overs. 

 K. Danskc Vidensk. Sclsk. Forhandl., 190S, A'o. 6, pp. Ji27-.'f6S). — The object 

 of the study was to ascertain the causes for the difference iu rate of growth 

 of bulbs planted iu October, December, and January. Experiments were con- 

 ducted during two years with tulips, tlie buU)S being planted in flower pots 

 and stored in a dark frost-free cellar until subjected to examination. The 

 time required for the shoots to attain definite lengths was noted, and the bulbs 

 with their leaves and shoots were subjected to a chemical examination in which 

 the dry matter, various forms of nitrogen, soluble carbohydrates, starch, and 

 pentosans were determined. 



From the data obtained the author is led to believe that the difference in 

 the growing power of bulbs planted in October, December, and January could 

 not be referred to differences shown by a quantitative or qualitative study of 

 the reserve material in the bulbs. The slow growth of the October bulbs was 

 not due to a lack of readily soluble compounds that go to make up the reserve 

 material in the bulb, but is believed to be associated with the metabolism 

 accompanying growth. 



The possible effect of cement dust on plants, G. J. Peikce (Science, n. ser., 

 30 {190'.)), So. 77 J, pp. 6.')2-(j.j.'f). — The author's attention has been called to the 

 deposit of light gray dust on p'lants and various surfaces in a valley not far 

 from San Francisco. Upon investigation it was found that the foliage of the 

 native and cultivated plants for a distance of more than G miles was covered 

 with dust from cement works. The upper surface of many leaves, such as 

 oak, willow, grape, etc., was thickly covered, but on glossy leaves, such as 

 peach, lemon, and orange, it was not held. On the fruits it was quite evident 

 and could not be removed without rubbing off the bloom.' On investigation 

 the material was found to be so finely ground and to cover the leaves to such 

 an extent that the exchange of gases in the leaves was prevented to a consider- 

 able extent, the stoniata in some cases being clogged with the fine particles. 



The conclusion of Haselhoff and Lindau (E. S. R., 14, p. 633) that cement 

 dust does no harm to vegetation in Germany since it is washed off by frequent 

 showers, is held not to apply in California, where the atmospheric conditions 

 are quite different, there being practically no rain after the leaves of deciduous 

 plants have developed. In some parts of California the frequent summer fogs 

 give rise to considerable moisture, but these together with the rains that may 

 be expected do not wash the cement from the leaves, but tend to form it into 

 a permanent crust. 



Vitality of seeds under water, J. J. Thornber (Arizona Sta. Bui. 60, pp. 

 438--'i'il ) . — On account of the fact that the Colorado River annually overflows 

 its banks, submerging the land from 2 to 6 weeks, the author investigated the 

 vitality of a considerable number of species of seeds which were submerged 

 for various periods of time. A preliminary account of these investigations 

 has already been noted (E. S. R., 20, p. 628). 



In general it was found that amber cane or common sorghum is the only 

 crop that can be sown successfully before a protracted flood period begins. 



FIELD CROPS. 



Field crop experiments, F. G. Krauss (Hawaii Sta. Rpt. 1908, pp. 65-8-i, 

 pis. Jf). — This is a continuation of work previously noted (E. S. R., 20, p. 137). 



A sketch of and data pertaining to the rice growing and milling industries 

 in Hawaii are presented, together with United States customs statistics on the 

 exportation and importation of rice for the five years ended June 30, 1907. 



During the year the third comparative test was made of 130 varieties of rice 

 originally obtained from this Department. Pure strains of some of the varieties 



