326 EXPERIMENT STATION" EECOED. 



were also confirmed in essential details in further experiments with Zea mays 

 and Phaseolus vulgaris. 



Experimental production of hyperplasia in plants, L. Petri (Atti R. Accad. 

 Lincei, Rend. CI. Sci. Fis., Mat. e 2^'at., 5. ser., 22 {1913), II, No. 10, pp. 509-516, 

 figs. 3). — A preliminary report is made showing some results obtained by in- 

 jecting solutions of peptone, urea, etc., of not over 1 per cent strength into 

 growing cortical tissue of stems and roots. 



Comparison of microphotographic views shows that the thickening of the 

 tissue is due mainly to a great enlargement of the cells individually. The 

 cell walls remain thin and tender. These indications of arrested development 

 are compared with effects observed to follow exposure to cold or puncture by 

 insects. 



Some experiments on the effect of external stimuli on the sporidia of 

 Puccinia malvacearum, W. Robinson {Ann. Bot. [London], 2S (1914), No. 110, 

 pp. 331-3JfO, figs. 7). — Cultures were made of spores of P. malvacearum in hang- 

 ing drop cells, in which the effect of various stimuli were tested. 



The sporidia were found, to be negatively heliotropic. Moisture and contact 

 were also found to affect the germ tubes. In the normal host plant a slender 

 growth from the swollen end of the germ tube penetrated the cuticle and outer 

 wall of the epidermis, bringing about a true infection, but this was not seen 

 to occur in other plants than the normal hosts. In the case of certain leaves, 

 as Pelargonium, Eucalyptus, and Primula, with glandular secretions, a definite 

 toxic effect was exerted on the sporidia and germ tubes in the immediate 

 neighborhood of the fragment of the leaf. The investigations did not disclose 

 why the normal hosts should be infected while other plants were not. They 

 did show, however, that the germ tube is irritable to light, to moisture to a 

 certain degree, and to contact. 



Morphological instability, especially in Pinus radiata, F. E. Lloyd '{Bat. 

 Oaz., 51 (1914), ^0. 4, pp. 314-319, pi. 1, figs. 2).— A description is given of a 

 proliferation of spur shoots occurring in the Monterey pine, which has also been 

 seen in other species of Coniferae. The tree described was growing near a cess- 

 pool and it is believed that the water relation of the plant was responsible for 

 the proliferation. A somewhat similar occurrence is reix)rted as having been 

 observed in P. to'da after injury. 



The effect of climatic conditions on the rate of growth of date palms, A. 

 E. Vinson {Bot. Oaz., 51 {1914), No. 4, pp. 324-327, pi. i).— The results are 

 given of observations of the effect of climate on the rate of growth of date 

 palms made at the cooperative date orchard, Tempe, Ariz. 



In these studies comparisons were made between the rate of growth and the 

 temperature. From the platted curves the rate of growth was found to be most 

 active, not at the period of highest maximum, but rather at the highest mini- 

 mum temperatures, which were warm nights in July, August, and sometimes in 

 September. By far the greater part of the total yearly growth was found to 

 occur in the last half of the year. 



The rate of maturing fruit was also investigated. It is thought to be prob- 

 ably influenced by the same factors as the rate of growth of foliage. 



The effect of shading on the transpiration and assimilation of the tobacco 

 plant in Cuba, H. Hasselbking {Bot. Gaz., 57 {1914), A'o. 4, pp. 257-286, fig. 

 i). — A report is given of experiments conducted in western Cuba to determine 

 the effect on transpiration and assimilation in the tobacco plant of the cheese- 

 cloth shade, which is frequently used in that region for shading tobacco. 



It was found under the climatic conditions of the region that the transpira- 

 tion of the tobacco plants grown in the open was nearly 30 per cent greater 

 than that of plants grown under cheese-cloth shade. The transpiration per 



