2 Allgemeines. — Ph3^siologie. 



II. Ucbersiclitsbilder über die Verteilung der Cysto- 

 lithen in Blättern. Kleinere Teile der Blätter werden in Porzellan- 

 Tiegel eingeascht. Die zurückgebliebenen weissen Lamellen werden 

 auf ein dünnes Lager von Kanadabalsam auf einen Objektträger 

 gelegt. Deckglas ist meist nicht erforderlich. Die Cystolithen treten 

 mit grossem Kontrast hervor, weshalb die Präparate sich auch für 

 mikrophotographische Aufnahme eignen. 



III. Anwendung von wasser gelöstem Phenol (90 Phe- 

 nol: 10 Wasser) für das Aufhellen pflanzenanatomischer 

 Objekte (besonders bei Untersuchungen über die Verteilung von 

 Oxalat- und kieselführenden Idioblasten). Das Kristallisieren unter 

 dem Deckglase wird durch Zusatz von etwas Glyzerin beseitigt, 

 und das Präparat kann tagelang unter dem Deckglas in dem Phe- 

 nolglyzerin verbleiben. Je nach der Menge des zugesetzten Glyzerins 

 kann die Aufhellung zweckmässig abgestuft werden. Nach Demon- 

 stration von Präparaten kann das Glyzerinphenol durch Glyzerin 

 ersetzt und bei nächster Demonstration wieder zugesetzt werden. 



Grevillius (Kempen a. Rh.). 



Kidd, F., The Controlling influence of carbon dioxide 

 in the maturation, dormancy and germin ation oi 

 seeds. L (Proc. Roy. Soc. Lond. LXXXVII. B. p. 408—421. 1914.) 



Experiments are described showing that germination can be 

 completelj?- inhibited by the presence of carbon dioxide, 20 to 30 

 per Cent according to the temperatures used. The inhibition is not 

 accompanied by injury, the seeds germinate at once after removal 

 from inhibiiory CO2 pressures Experiments in the field showed that 

 this action of COo ma}?^ actuall}'' occur in nature; if a quantity of 

 green plant material is buried deeply in the ground, seeds planted 

 in the soil over this decaying material are inhibited in their ger- 

 mination by the COo produced beneath them. The fact that in 

 mustard seedlings Suspension of vitality continues, even after the 

 external CO2 has been removed, suggests an explanation of the 

 common occurrence of dormant seeds of this plant in lields, and 

 possibly of other natural cases of dela5^ed germination. 



F. Cavers. 



Kidd, F., The Controlling influence of carbon dioxyde 

 in the matyration, dormancy and germination of 

 seeds. II. (Proc. Roy. Soc. Lond. LXXXVII. B^p. 609-625. 1914.) 



The inhibitory effect of CO.2 on germination previously descri- 

 bed (see foregoing abstract) is dealt with in relation to temperature 

 and oxygen supply. As to temperature the result obtained is unu- 

 sual, the Inhibitor}^ action being greater at low than at high tem- 

 peratures. At 3^ C. complete inhibition was obtained with 4%. while 

 at 17° as much as 24% had to be employed to obtain the same 

 result. Varying partial pressures of oxj^gen also affcct the inhibi- 

 tory action of CO^ but to a less degree than temperature. Thus 

 witli 50/0 ox3^gen, 15% COo produced inhibition; with 20% oxygen, 

 270/0 CO2 was necessary. The author cmphasises the fact that the 

 adjustments of the moist seed b}" which it is enabled to continue 

 dormant in the presence of oxygen and water, rather than those of 

 the dry seed, are likely to have formed the central problem of 

 seed life in nature. A low temperature and a diminished ox3^gen 

 supply are often the natural conditions of a seed's environment in 



