Biologie. — Morphologie etc. 131 



The conclusions are that the northern evergreen Coniferae are 

 architectural xerophytes in which the extensive surface exposed 

 as a whole renders it necessary for the individual leaves to be 

 xeromorphic in form and xerophytic in structure. The tracheidal 

 structure is well-suited to their xeropliytic evergreen leaves, and 

 a similar type of wood may occur in dicotylous trees with ever- 

 green leaves, e. g. Querciis. The tracheidal structure is not a bar 

 to progress, and more probably provides a safety mechanism that 

 is a defence against extinction. The Coniferae are more easilj'' 

 injured and are attacked by more foes than dicot37-lous trees. This 

 greater vulnerability may in part explain their defeat and extinction 

 in past ages. W. G. Smith. 



Velenovsky, J., Einfluss der Hitze auf die Vegetation 



(Pfiroda. X. p. IC sq. 1911/12. böhmisch.) 



In den Hitzeperioden des Jahres 1911 konnte man gut beobach- 

 ten, welche Pflanzen in Mitteleuropa am besten Hitze ertragen 

 und so auch auf ihre Herkunft schliessen lassen, es sind haupt- 

 sächlich Xerophyten und Steppenpflanzen. Nicht beschädigt zeigten 

 sich CoHvolvulus arvensis, Coronüla varia, Eqidsetum arvense, Cav- 

 lina acaulis, einige Cichoriaceen, z. B. Cichorium Intyhiis, das noch 

 besser als sonst blühte und reifte; ferner Ononis spinosa, Pimpinelia 

 Saxifraga, Biipleurum falcattim auf heisscn Felsen, Seseli coloratum, 

 Daiicus. Cnrota, die widerstandsfähiger als Seduni sich zeigten ob- 

 gleich sie keine speciellen anatomischen oder biologischen Einrichtun- 

 gen aufzuweisen haben; prächtig blühte auch Eiyngiuni campestre. 

 Trifolium pratense ging häufig zu Grunde, dagegen erhielt sich Me- 

 dicago sativa sehr gut. Interessant ist auch, dass das hnpatieiis noli 

 tangere fast nur kleistogame Blüten gebildet hat. 



Jar. Stuchlik (München). 



Bayüss, J. S., Note on some Nuclei found in Grasses. (New 

 Phyt. XL NO 4. p. 128. 1 fig. 1912.) 



The author writes this note to draw attention to the frequent 

 occurrence of elongated nuclear in the actively growing stelar 

 tissue at the bases of the internodes in grasses. These nuclei may 

 be 20 or 25 times as long as they are wide. 



Agnes Arber (Cambridge). 



Farmer, J. B., "Nuclear Osm osis" and its assumed Relation 

 to Nuclear Division. (New Phyt. XL N« 4. p. 139—144. 1912.) 



This paper is devoted to a critical review of two papers by 

 A. A. Lawson (The phase of the nucleus known as synapsis, 

 Trans. Roy. Soc. Edin. Vol. XL VIT, p. 591, 1911 and Nuclear 

 Osmosis as a factor in mitosis, Trans. Roy. Soc. Edin. Vol. XLVIII, 

 p. 137, 1911). The author finds himself unable to accept Dr. 

 Lawson's theory. Agnes Arber (Cambridge). 



Hollinshead, M. H., Notes on the seedlings of Conimelina 

 communis. (Contr Bot. Lab. Univ. of Penna. 3. p. 275— 287. pl. 4 — 5. 

 1911.) 



The author of this paper first gives a short historic resume 



