Physiologie. — Palaeontologie. 69 



Leitch, I,, Some experiments on the influence of tempe- 

 rature on the rate ofgrowth in Pisum sativum. (Ann. Bot. 

 XXX. p. 25-46. 1916.) 



A considerable amount of work has been done on the influence 

 of temperature and growth during experiment periods of twenty 

 four hours and upwards. In the present series one set of experi- 

 ments dealt with the long experimentation time of 22\ hours, the 

 second set with very Short times, reckoned in minutes or half hours. 



\^^ series. The peas were soaked at a uniform temperature of 

 15°— 20° C. in an electric thermostat for 22^ hours. Seventy peas 

 were then placed on a special germinating apparatus and left for 

 two days. Thirty five with the most uniform roots were measured 

 and placed in a gas thermostat regulated to various temperatures 

 on different days, and measured after a further 22| hours. Open 

 air experiments gave results for temperatures at or about zero. 



2"^^ series. After soaking and germination the peas were fixed 

 singly into tubes so arranged that air had free access to the roots, 

 sufificient moisture also being supplied. A beaker of water regulated 

 to the required temperature served as a water bath, and measure- 

 ments were made by microscope readings at frequent intervals. 

 The influence of light and darkness under these conditions was 

 tested. With high temperatures it was necessary to take readings 

 at one minute intervals on account of the approach towards the 

 death point. Results were expressed as tables and graphs. 



The relation of growth to temperature can be expressed as a 

 uniform curve from —2° C. to about 29° C. This curve much resem- 

 bles those found b}^ Krogh for "Standard metabolism in animals", 

 and by Kuijper for respiration in Pisum. Above 29° C. the relation 

 can no longer be expressed as a curve, but for each higher tem- 

 perature a different curve must be constructed to express the rate 

 of growth in successive time intervals. Between 30° C. and 40° C. 

 these curves are not simple time curves, and no extrapolation is 

 possible. 



For growth there is a well-marked Optimum temperature. A 

 further point, the maximum-rate temperature, is distinguished and 

 defined. For growth the minimum temperature is — 2° C; the maxi- 

 mum 44.5° C; to the degree of accuracy found possible the Optimum 

 temperature is between 28° C. and 30° C, and the maximum-rate 

 temperature is 30.3° C. W. E. Brenchley. 



Leuthardt, F., Ueber die Keuperflora von der Moderhalde 

 bei Pratteln (ßaselland). (Verh. Schweizer, naturf. Gesells. 

 96. Jahresvers. 1913 in Frauenfeld. V. Teil. Aargau, Sauerländer, 

 p. 187—189. 1914.) 



Die Pflanzenftihrenden Schichten am genannten Orte, wo man 

 seit 1788 nach Steinkohle suchte, gehören der Schilfsandsteinzone 

 und entsprechen dem Pflanzenhorizont von Neue weit. Pflanzliches 

 Material liegt im Museum Basel. Bisher fand man: Bambusium 

 Imhoffi Heer, Voltsia heterophylla Br. (Zapfenschuppe), Widdringto- 

 nites Keiiperianus Heer, viel an Ptevophyllum , 3 Equisetum- Arien, 

 *Schi3oneura Meriani Heer, ferner die Farne *Taeniopteris angusti- 

 folia Schk., *Asteyocarpus Meriani Feri., Peropteris Steimnülleri Heer, 

 Gleichenites gracilis Heer. Die mit * bezeichneten Arten sind für 

 die Moderhalde charakteristisch. Auffallend ist das Fehlen von 

 Baiera hircata Heer, Merianoptevis angustata und Pecopteris Rüti- 



