136 EXPERIMENT STATlOlSr EECOKD. 



tions may renew growth at any time during the period of rest, which is really 

 enforced. 



Oxidation in healthy and diseased apple bark, D. H. Rose {Bot. Gaz., 60 

 (1915), No. 1, pp. 55-65). — An account is given of an investigation made re- 

 garding oxidase activity in the hark of apple trees, all the tests employing Bun- 

 zel's simplified oxidase apparatus (E. S. R., 32, p. 508). 



It is stated that extract of apple-tree bark affected with Illinois canker, due 

 to Nummularia discreta, causes greater and more rapid oxidation of pyrogallol 

 than does the extract of healthy bark. Diseased bark extract is less acid than 

 that of healthy bark, apparently justifying the conclusion that within the range 

 of concentrations here employed, oxidation is in approximately inverse ratio to 

 the acidity of the extract. 



Oxidases are very .sensitive to small variations in the acidity of the solution 

 in the oxidase apparatus. 



The hypothesis is offered that the gradual slowing down of oxidation in this 

 apparatus is brought about by acccumulation of oxidation products, probably 

 acetic and oxalic acids, and not by using up of the oxidase through chemical 

 combination of oxidase and oxidizable substance. 



Parthenogenesis, parthenocarpy, and phenospermy in Nicotiana, T. H. 

 GooDSPEED {Univ. Cal. Pubs., Bot., 5 (1915), No. 8, pp. 2.^9-272, pi. i).— This 

 gives a fuller account of the work previously notetl (E. S. R., 33. p. 43.5). 



In the majority of these parthenocarpic fruits empty .see<ls wore produco<l in 

 large numbers. These were mostly smaller than the self-fertilized seed of the 

 same plant. For this type of seed production, with or without pollination, the 

 term phenospermy is suggested as synonymous with " empty " or " abortive." 



A few of the seed from the parthenocarpic fruits were neither partheno- 

 genetic nor phonospcrTnlc, containing traces of endosperm only. 



The biology of Melampsora lini, A. Buchheim {Bcr. Dciit. Bot. GcscU., 33 

 (1915), No. 2, pp. 73-75). — Reporting tests with uredosporcs of if. Uni on 

 several species of Linum, the aullmr states that so far as reliable results have 

 been obtained this fungus shows a liigli d(»groe of specialization. 



Some filamentous fungi tested for cellulose destroying power, F. M. 

 Scales (Bot. Gas., 60 (1915), No. 2, pp. lJi9-153).—li is stated that in a study 

 previously noted (E. S. R., 28, p. 627), several cellulose destroying filamentous 

 fungi were identified, and two new species were found. One of the latter is 

 said to produce a very active cytase. The present report gives results of an 

 attempt to determine more species capable of exercising this function. 



The cellulose-destroying power of about 30 species of Penicillium and 10 

 species of Aspergillus was determined with two different nitrogen sources, an 

 annnouium sulphate cellulose agar and a peptone cellulose agar being employe<l 

 for this purpose. The results as tabulated are positive in all but eight cases 

 for the medium containing the ammonium salt, and the appearance of negative 

 results for the peptone alone in some of the other cases is discussed. 



The reaction of bacteriologic culture media, W. M. Cl.vrk (Jour. Infect. 

 Diseases, 17 (1915), No. 1, pp. 109-136, figs. 7).— This deals with the applica- 

 tion of the principles of hydrogen ion concentration in culture media as relatetl 

 to the titration method. 



The differentiation of bacteria of the colon-aerogenes family by the use of 

 indicators, W. M. Clark and H. A. Lrns (Jour. Infect. Diseases, 17 (1915). 

 No. /, pp. 160-173, figs. 2). — It is claimed that by tliesc studies, as described, a 

 simple diagnostic test has been established, tlie ri^sults of which correlate per- 

 fectly with the gas ratios of the two main groups of the colon-aerogenes bacteria. 



