56 Varietäten, etc. — Physiologie. 



cross pollination off lax. (Journ. of Genetics. V. p. 189—197. 

 1916.) 



The main object with which the work described in the present 

 paper was commenced was to effect a crossing between a flax 

 which contains cyanogenetic glucoside and enzyme and one which 

 does not. 



It had been noted previously that yellow-flowered species of 

 fiax seemed devoid of enzyme. This Observation was confirmed 

 by a large number of observations and attempts made to cross 

 yellow-flowered species with blue- and with white flowered species. 

 The following species were used In crosses. Yellow: L. fiaviim, 

 L. maritimum, L. arboreum. Red L. grandiflorum. White or Blue: 

 L. monogynum, L. perenne, L. austriacum, L. narbouense. These 

 were crossed in various ways, many hundred times in some cases, 

 entirely without result except in two cases: viz. 11 plants from 

 L. monogynum X £- arboreum. and 3 plants from L. monogynum 

 X L. narbonense. These plants all contained glucoside and enzyme 

 and resemble in general characters the enzyme-containing parents 

 except for the fact that they have shown no signs of Coming into 

 fiower. 



During the experiments confirmation was not obtained of 

 Darwins' Statement that L. perenne yields no seed as the result 

 of illegitimate pollination. 



In addition to these experiments with isolated plants, obser- 

 vations were made of the characters of the plants when varieties 

 were raised out of doors in considerable numbers in view of the 

 opinion prevading in some flax-growing districts that fiax is unstable 

 and readily loses certain of its characters. Variations in the crops 

 were observed, but only such as could be explained on the basis 

 of the segregation of allelomorphic characters when a hybrid is 

 propagated by seed. 



Attempts are also being made to isolate improved strains of 

 flax for commercial purposes, both in respect to fibre and oil. As 

 regards the former, a considerable increase in stature (as much as 

 10 inches) and also in the uniformity of the crop has been obtained 

 as the result of selection. 



Work has not proceeded far enough as regards the latter to 

 Warrant anything definite being said. W. Neilson Jones. 



Babak, E., lieber die Wärmeerscheinungen der Orga- 

 nismen. (Biothermik). („Aus der Natur". XIII. p. 10-20. 

 1916/17.) 



Wie greifen nur das Botanische heraus: Schon infolge der durch 

 starke Transpiration bewirkten Wärmeabgabe kann sich ein Baum 

 nicht nur durch eigene Wärmeerzeugung nicht erwärmen, sondern 

 bleibt gewöhnlich, sogar von der Sonne beschienen, kühler als die 

 Umgebung. Die Temperatur des Pflanzenkörpers folgt in der Haupt- 

 sache der Temperatur des Aussenmediums, sie kann allerdings die 

 letztere in besonderen Fällen — bei erheblicher Wärmebildung 

 und bei Verhältnissen, die einer Wärmestauung günstig sind — 

 mehr oder weniger übertreffen [Leick]: so z. B. unter natürlichen 

 Bedingungen bei den blühenden Kolben gewisser Araceen bis um 

 20° C, bei der mächtigen Blütenanhäufung bei den Cycadeen und 

 Palmen, in den riesigen Blüten von Victoria regia usw., hier überall 



