52 SCIENCE PROGRESS 



period of winter annual forms, as this rest period can be elimi- 

 nated under suitable experimental conditions. We maybe able 

 to speak of properties which, in co-operation with climatic con- 

 ditions, determine the natural vegetation period. Such pro- 

 perties are, in addition to a characteristic after-ripening period 

 in the seed, a specific low-temperature requirement, and a 

 specific frost-resistivity, but also here difficulties arise on 

 closer examination. A specific frost-resistivity of an organism 

 does not exist. Experience shows that the same plant has 

 different powers of resistance to frost at different stages of 

 development. Consequently we cannot speak of an autonomous 

 frost-resistivity, but only about inheritance of a specific pro- 

 perty to produce under certain external conditions more or 

 less resistance to frost. Similarly concerning the requirements 

 in regard to low temperature the author has shown that the 

 flowering of winter annual grasses is bound up with the action 

 of low temperature, but it must be observed that, according to 

 the age of the plant, different low temperatures must be applied. 

 But even with plants of the same age the same low tempera- 

 ture acts differently according to other external conditions. 

 A temperature which, in light and air rich in carbon dioxide, 

 will result in flower formation at a later stage, does not do this 

 if illumination or carbon dioxide are insufficient. The author 

 arrives at a conclusion in regard to the inheritance of plant 

 properties similar to that of some investigators in genetics, e.g. 

 Baur (" Einfiihrung in die Exakte Vererbungslehre," Zweite 

 Aufl., Berlin, 19 14), who cites the case of Primula sinensis rubra 

 and P. sinensis alba, in which the colour oi the flower is bound 

 up with a certain temperature, for if P. sinensis rubra is culti- 

 vated at about 30 C. the colour becomes white. As Baur 

 says : " Only a certain specific type of reaction to the external 

 world is inherited, and what we perceive with our senses as 

 external characteristics are only the result of this reaction on 

 a chance combination of external conditions under which the 

 individual has developed." 



ZOOLOGY. By Prof. Chas. H. O'Donoghue, D.Sc, F.Z.S., University 

 of Manitoba, Winnipeg, Canada. 



Invertebrata. — The theory put forward by Child that there 

 is an axial metabolic gradient in Tubularia has been reinvesti- 

 gated by Banus (" Is the Theory of Axial Gradient in the 



