180 



SCIENCE 



[N. S. Vol. XLI. No. 1048 



Senile Changes in the Leaves of Vitis vulpina and 

 Certain, other Perennial Plants: H. M. Bene- 

 dict. 



It has been found by an investigation extend- 

 ing through a period of seven years that in the 

 leaves of V. vulpina and other plants there oc- 

 curs evidence of seniUty. Similarly aged leaves 

 of differently aged plants (age being reckoned 

 from date of last reproduction from seed) show 

 marked differences in the extent of veinage. The 

 aggregates of mesophyll cells enclosed within the 

 smallest veinlets^ which may be termed vein-islets, 

 are uniformly smaller in leaves of old plants than 

 in leaves of young plants. In other words, leaves 

 of old plants have a higher percentage of vascular 

 tissue than leaves of young plants; consequently 

 they are less efficient photosynthesizing organs, 

 and this has been proved by experiment. A for- 

 mula is presented showing the method for deter- 

 mining age of Vitis vulpina from the character of 

 its veinage. The juvenile veinage is restored only 

 after sexual reproduction. Finally, a theory of 

 sexuality is proposed, based upon loss in permea- 

 bility. 



Influence of Certain Salts on Nodule Production 



in Vetch: Me. Kno. 



Calcium salts are essential for nodule produc- 

 tion in vetch. The substitution of borium or 

 strontium to a limited degree permits also of 

 nodnle development. The relation of balanced 

 solution to nodule production has also been in- 

 vestigated. 



Physiological Studies of Bacillus Badicicola of Soy 



Bean: J. K. Wilson'. 



This investigation confirms earlier work as re- 

 gards the influence of nitrates on nodule produc- 

 tion, and indicates in addition that sulfates in 

 relatively weak concentration inhibit the process. 

 Chlorides and phosphates stimulate nodule pro- 

 duction, while ammonium salts are inhibitory. The 

 significant fact was developed that while nodule 

 development was prevented by the presence of 

 nitrates, phosphates and ammonium salts, yet the 

 organism retained its vitality in the presence of 

 these salts. Whether the effect of the salt is upon 

 the root, such as to make it resistant, or upon the 

 organism can not yet be stated. 



Direct Absorption and Assimilation of Carbohy- 

 drates by Green Plants: Lewis Knxjdson. 

 Confirming and extending the work of Laurent, 

 Molliard and others, it has been found that a va- 

 riety of plants are able to absorb and assimilate 



various sugars, including lactose. Plants em- 

 ployed are timothy, vetch, onion, radish, pea, cab- 

 bage, clover, flax and corn. Lactose has been 

 found to be utilized by vetch, radish and onion 

 but not by timothy. For corn the sugars in order 

 of ' ' preference ' ' by the plant are glucose, levu- 

 lose, cane sugar and maltose ; for vetch, cane sugar, 

 glucose, maltose and lactose. Experiments on the 

 influence of concentration of the sugar on growth, 

 influence of sugars in respiration and color pro- 

 duction have also been made. A study of the 

 influence of sugars in enzyme production is now 

 progressing. 



A Preliminary Study of the Chlorophyll Com- 

 pounds of the Peach Leaf: Howard S. Reed 

 AND H. S. Stahl. 



The investigations were undertaken with espe- 

 cial reference to the foliage of peach trees having 

 ' ' yellows. ' ' The chlorophyll compounds were ex- 

 tracted and separated by the use of inactive sol- 

 vents. The diseased leaves differ from the healthy 

 in both the quality and quantity of chlorophyll 

 derivatives extracted. The derivatives have been 

 identified by their color, solubility, spectra and 

 other properties. 



Among others, the following derivatives have 

 been found in healthy peach leaves: chlorophyll a, 

 chlorophyll b, phytorhodin, chlorophyllin, phseo- 

 phytin, phseophorbide, methyl-phasophorbide, methy- 

 chlorophyllid, phytoehlorin, carotin, and xantho- 

 phyll. 



As the disease advances there is a decrease in 

 the quantity of both chlorophyll and chlorophyll 

 derivatives. The diminution of the green series 

 is greater than that of the yellow-brown series. 

 Bespiration in Apple Leaves Infected loith Gymno- 

 sporangium: Howard S. Reed and 0. H. Cra- 



BILL. 



The respiration of apple leaves has been studied 

 with reference to the pathological effects of infec- 

 tion. Foliage was studied at various stages in the 

 development of the disease, using both Ganong^ 

 respirometer and Sach's baryta methods. The 

 diseased leaves uniformly produce more carbon- 

 dioxide than healthy leaves in the same intervals. 

 Various factors influence the process. 

 The Absorption and Excretion of Electrolytes by 

 Lupinus albus in Dilute Simple Solutions of 

 Nutrient Salts: R. H. True and H. H. Bart- 



LETT.l 



1 Office of Plant Physiological and Fermenta- 

 tion Investigations, Bureau of Plant Industry, U. 

 S. Department of Agriculture. 



