330 Bacteriologie. — Lichenes. 



Compounds on the growth of Asotobacter. The study was induced 

 by the theory that the soll contains organic substances which are 

 deleterious to plant growth and which are important factors in in- 

 fluencing soil fertility. It is, therefore, interesting to determine if 

 this toxicity exten ds to the lower plants. Asotobacter was chosen as 

 a representative to the soil flora since it is of recognized importance 

 in the maintenance of soil fertility and its growth may be accura- 

 tely measured by analytical means. The Compounds used were 

 those likely to be constituents of the soil. The results are: Fixation 

 of nitrogen by Asotobacter is only slightly influenced Dy most of 

 the Compounds investigated. A depression is noted in many cases 

 but it is usually the result of a relatively high concentration of the 

 Compound used. Hydroquinone and Salycylic aldehyd revealed the 

 most toxic properties of any Compounds studied. Esculin, Quinic 

 Acid and Borneol afforded marked Stimulation to the growth of the 

 organism. The effects of the Compounds on Asotobacter are not as 

 a rule, in accord with what has been reported of their action on 

 the higher plants. In concentrations which are fatal to certain 

 higher plants, many of the Compounds only slightly depressed 

 fixation. A number of nitrogenous bodies were investigated. Such 

 Compounds as Nicotine, Picoline, Guanidine, and Skatol exhibited 

 toxic properties commensurate to those usually ascribed to these 

 substances. Caffeine appeared to stimulate the growth of the orga- 

 nism. Many of the nitrogenous Compounds used which have been 

 reported as beneficial to higher plants exercised a marked depres- 

 sion on fixation. It appears that the simpler Compounds were more 

 pronounced in this respect than were the more complex ones. It is 

 suggested that this condition is not one of toxicity but that the ni- 

 trogen of the Compounds was utilized by Asotobacter in preference 

 to that of the atmosphere. Urea, GlycocoU, Formamide and Allan- 

 toin were especially active in depressing fixation. 



Matouschek (Wien). 



Schade, A., Die „Schwefelflechte" der Sächsischen 

 Schweiz. (Abhandl. naturw. Ges. „Isis" Dresden, p. 28—44. 

 1916.) 

 Verf. befasst sich mit jenen Flechten , welche, unter dem Namen 

 „Schwefelflechte", oder fälschlich „Leuchtmoos" bekannt, in der 

 Sächsischen Schweiz die Sandsteinfelsen auf weite Strecken 

 mit lebhaft gelber Farbe bekleiden. An dieser Erscheinung beteili- 

 gen sich fünf Flechten. In erster Linie Lepraria chlorina Fic, ein 

 stätig steriles Lager, dessen systematische Zugehörigkeit demnach 

 noch unbekannt ist. Dann Biatora lucida (Ach.), welche mehr am 

 Grunde der Felsen auftritt und die höchsten Zinnen meidet und 

 Chaenotheca arenaria (Hampe). Diese beiden Arten fruktifizieren 

 häufig. Vereinzelt und ohne besonders aufzufallen kommen noch 

 hinzu Coniocybe furfuracea (L.) und das durch seine Seltenheit be- 

 merkenswerte Calicium coryneUum Ach. Diese fünf Flechten wer- 

 den einzeln geschildert; über ihren Bau, ihr Auftreten und ihre 

 geographische Verbreitung eingehende Angaben gebracht. Mehrere 

 der aufgetauchten Fragen mussten derzeit unerledigt bleiben; 

 hoffentlich wird Schade später die Zeit finden, auch diese zu 

 besprechen. Zahlbruckner (Wien). 



