Pflanzenkrankheiten. — Bactcriologie. — Pteridophyten 467 



susceptibilily to disease, but cannot counteract the effect of large 

 quantities of nitrogenous manures. Plants which are semistarved as 

 regards nitrogen exhibit a considerable degree ofimmunity. Lithium 

 salts were observed to produce a certain immunity, while nitrates 

 of lead and zinc render plants extremely susceptible, 



A variety of wheat which ist almost immune to a disease, (such 

 as Little Joss to ^''ellow rust) tends to retain its immunitj^ even 

 when supplied with excess of nitrogenous food-material. 



Increased immunity does not appear to be due to a lack of food- 

 material available for the fungus in the host. 



E. M. Wakefield (Kew). 



Bottomley, W. B., Some Conditions influencing Nitro- 

 gen Fixation by Aerobic Organisms. (Proc. Roy. Soc. 

 LXXXV. B. p. 466—468. 1912.) 



Experiments were carried out with Pseudomonas and Asotobacter 

 in Order to obtain a carbohydrate source of energy equally efficient 

 for both organisms. 



A suitable medium for the cultivation of a mixed culture of 

 Asotobacter and Pseudomonas containing dextrin as the carbohy- 

 drate, is given in the following formula: 



Distilled water, 100 c.c, di-potassium phosphate 0.2 gr., dextrin 

 1 gr., magnesium sulphate 0.02 gr., basic slag 0.4 gr. 



T. Goodey. 



Pereival, J. and G. Heather Mason. The Micro-flora of 

 Stilton- Cheese. (Journ. Agr. Sei. V. 2. p. 222-229. 1913.) 



The number of organisms in a Stiltoncheese reaches its maxi- 

 mum during the first four days, from 1000 to 3000 millions per 

 gram being often found, 900/o of which are cocci or short rods 

 capable of producing lactic acid in milk. The numbers decrease 

 slowly up to the time of complete ripeness, when the cheese con- 

 tains 50 to 100 millions per gram. 



In all the Stilton cheeses examined, five organisms were found 

 to be characteristic, namely, 1) Streptococcus lacticus, 2) a form of 

 Bacillus acidi lactici, 3) a species of Tyrothrix, 4) PenicüUuni glau- 

 cum, 5) a round form of "Torula", sometimes accompanied or 

 replaced by an oval form. The Penicillium develops in the later 

 stages of ripening, and it was found to be checked in its growth 

 by the presence of the Tyrothrix. 



In cheeses where Starters had been used a large-celled form of 

 Streptococcus lacticus was present. E. M. Wakefield (Kew). 



Bower, F. O., Cheiropleuria bicuspis (81.) Pr. (Nature. XCI. 2282. 

 July 24th. 1913.) 



This uncommon Malayan Fern bears no scales only hairs. 

 Its leaves show a certain relation to those of Dipteris; it appears 

 also to approach Platyceriu)n though its nearest relations are to the 

 Matonineae. It possesses a mixed sorus but is relatively simple 

 anatomically, the rhizome being constantly protostelic and the leaf- 

 trace originating as a Single mesoxylic Strand that eventually be- 

 comes bifascicular. Isabel M. P. Browne (London). 



