222 EXPERIMENT STATION RECORD. 



Report upon sewage sludge as a manure, H. M. Wilson (Wakefield, Eng- 

 land: West Riding Rivers Board, 1913, pp. 10; abs. in Wasser u. Abicasser, 9 

 (1915), No. 4i PP- 106-108). — Analyses of sewage sludge from 22 sources in 

 English cities, with reference to their content of fertilizing constituents, are 

 reported, which show that the nitrogen varied from 0.9 to 3 per cent of the dried 

 sludge, the phosphoric acid from 0.2 to 2.6 per cent and in one case reached 5.5 

 per cent, and the potash from a trace to O.S per cent. 



Objection to the use of sewage sludge for fertilizing purposes is due to its 

 high fat content and to its being in a form inconvenient to handle. 



Analyses of rocks and minerals from the laboratory of the "United States 

 Geological Survey, 1880-1914, F. "W. Clakke (U. S. Gcol. Survey Bui 591 

 (1915), pp. 376). — This report brings together the results of analyses of rocks 

 and minerals from different parts of the United States made by the U. S. Geo- 

 logical Survey during the past 34 years, together with bibliographic and petro- 

 graphic data. In the analyses of minerals, sections are included dealing with 

 different phosphates and nitrates. Other data are included which may be of 

 importance in a study of the soils or of natural structural materials of a region. 



AGEICULTTJRAL BOTANY. 



Senile changes in leaves of Vitis vulpina and certain other plants, H. M. 

 Benedict (Xcw York Cornell Sta. 21em. 7 (1915), pp. 281-370, figs. 7). — On 

 account of its possible bearing on the vitality of plants continuously propa- 

 gated asexually, the author has conducted an inve.stigation on the possibility of 

 senile changes, the studies being made on leaves of V. vulpina and some related 

 plants, especial attention being paid to changes in venation due to increase 

 in age, a brief account of which has been previously noted (E. S. R.. 32, p. 728). 



In addition, comparisons were made of photosynthetic activity of leaves from 

 young and old plants, respiration, imbibition, cellular changes, effect on nucleus 

 and cytoplasm, etc. 



The vein islets in the leaves of T. vulpina were found to become smaller as 

 the leaves became older, due to the encroachment of vascular tissue. Leaves 

 borne on plants vegetatively reproduced showed vein islets similar to the plant 

 from which the original cuttings were secured. The same difference with age 

 was found to occur in plants of T. bicolor, and apparently the same condition 

 exists in a number of other woody perennials. The decrease in the size of the 

 islets means a reduction in the number of photosynthesizing cells, and the evi- 

 dence shows a decrease in the rate of photosynthesis as well as in the rate of 

 respiration. The leaves of young vines were found to have a greater capacity 

 for imbibing water than the leaves of old vines, which is believed to be the 

 result of less vascular tissue in the former. There is thought to be an increase 

 in the number of stomata per square millimeter, but a decrease in the size of the 

 stomatal aperture and of guard cells. In the size of the palisade cells, and prob- 

 ably in the mass of nuclei of border parenchyma cells. 



Discussing the results as to the significance of senile changes to the problem 

 of the running-out of vegetatively propagated fruits, the author concludes that 

 there are specific morphological changes in the leaves as the plant grows old, 

 which appear to be independent of external conditions, and. so far as prelimi- 

 nary investigation goes, the results tend to support the view that propagation 

 by cuttings does not prevent the progress of senile degeneration in the tissue 

 of the cuttings. 



A bibliography is appended. 



