576 



SCIENCE 



[N. S. Vol. LIII. No. 1382 



celium within the host. Six days after inoc- 

 ulation, only five out of a hundred appres- 

 soria had entered. Material taken eight, ten, 

 and even twelve days after inoculation still 

 showed numerous appressoria and a relatively 

 limited number of infections. For greater 

 accuracy, counts were made and the results 

 tnLulated as follows: 



No. of Days Total No. 



after Inocu- of Sporelings No. of Percentage of 



lation Counted Entries Entries 



6 100 5 5 



8 133 14 10 +1 



10 77 7 9 



12 145 16 11 + 



Under the conditions of this experiment, 

 only about ten per cent, of the young rust 

 fungi enter. The other ninety per cent, re- 

 maia outside the stomata until they dry and 

 fall off. By the twelfth day, under green- 

 house conditions, practically all the appres- 

 soria are withered and collapsed. 



Tangential sections of Kanred and Mindum 

 leaves were examined. In these the stomatal 

 slit was measured in length, in width at center 

 and at its widest point, which is near the end, 

 and averages taken. The same was done with 

 Mindum, a durum variety somewhat resistant 

 to this strain of rust. The stomatal aperture 

 in Kanred is extremely long and narrow, 

 while that of Mindum, a less resistant variety, 

 is short, and very variable in width, the aver- 

 age width being about twice that of Kanred. 

 In Mindum, the rust sporeling enters freely, 

 while in Kanred nine tenths of them are ex- 

 cluded. It is possible that the naturally small 

 stomatal opening of Kanred is still further 

 narrowed by the action of the guard cells when 

 an appressorium comes in contact with the 

 stoma. A more comprehensive and fully il- 

 lustrated account, including similar observa- 

 tions on other varieties of wheat, and report- 

 ing resistance phenomena which follow actual 

 infection, is now in preparation. 



Ruth F. Allen 



College op Ageiculture and United 

 States Depjvktment of Agricul- 

 TUEE, Cooperating, 

 Berkeley, California 



THE AMERICAN CHEMICAL SOCIETY 



ROCHESTER MEETING 

 DIVISION OF PHYSICAL AND INORGANIC CHEMISTRY 



H. N. Holmes, chairman 

 S. E. Sheppard, secretary 



Symposium on Contact Catalysis 

 • Platinum MacTc and car'bon monoxide. Esteri- 

 fication ly silica gel: C. H. Milligan and E. 

 Emmet Eeid. A mixture of equivalent amounts 

 of acetic acid and ethyl alcohol has been passed 

 over silica gel at 150°, 250°, 350° C. It has 

 been found that silica gel is a very active catalyst, 

 more than twice as active as titania, the best cata- 

 lyst previously known for this reaction. When the 

 mixture is passed rather slowly at 150° the per- 

 centage of esterifieation is 75 to 80, which is much 

 beyond 67 per cent., the accepted limit for this 

 reaction. 



Adsorption hy oxide catalysts and the mecluinism 

 of oxidation processes: A. P. Benton. 



Dissociation of some mixed oxides: J. C. 

 Frazer. 



The adsorption of gases iy metallic catalysts: 

 H. S. Taylor and R. M. Burns. The adsorptions 

 of hydrogen, carbon monoxide, carbon dioxide and 

 ethylene by finely divided nickel, cobalt, iron, cop- 

 per, palladium and platinum has been found to be 

 of a specific character quite different in nature 

 from adsorption by porous inert adsorbents of the 

 charcoal type. The extent of adsorption was 

 shown to be a function of the mode of preparation 

 and to be especially less pronounced the higher the 

 temperature at which the metal was prepared. The 

 analogy of this fact with the corresponding facts 

 of catalytic behavior has been noted. Adsorption 

 isotherms at 25° C. of hydrogen with nickel, and 

 of carbon monoxide with copper have shown that 

 adsorption increases rapidly with increasing par- 

 tial pressures below 300 mm. and becomes prac- 

 tically independent of pressure above this pres- 

 sure. 



The action of nickel on diethyl ether: A study 

 in contact catalysis. Freliminary report : Francis 

 L. Simons. A report is given of preliminary work 

 in the study of the catalytic decomposition of 

 ether by nickel. The study was undertaken in the 

 hope of throwing light on the mechanism of the 

 action of nickel on alcohol and the simpler esters. 

 The apparatus used is described in detail and the 

 general procedure given. From the results so far, 

 it appears that ether is decomposed into H,, C^Hi 

 and OH3CHO, as Bancroft suggests. The compo- 



