614 Varietäten, Descendenz, Hybriden. — Physiologie. 



tational. He regards the whole differentation of the two Orders as 

 entirely an expression of the dorsiventrality forced upon them by 

 their plagiotropic growth, Agnes Arber (Cambridge). 



Kapteyn, J, C, Tree growth and meteorological factors. 

 (Recueil des Trav. bot. XL p. 70-82. 1914.) 



The investigation has been made over 30 years ago but its 

 evident incompleteness, has up to the present withheld the writer 

 from Publishing his results, only in some lectures publicity was 

 given to them. 



The writer now published his investigation in the hope that it 

 might help in calling t'orth more fundamental work from others. 



The growthrings of trees were studied as a means of finding 

 a connection between the weather in past years and the tree growth. 

 From different reasons oak trees only were studied and especially 

 oak trees collected in the forests along the Main, the Moselle and 

 some forests not far from the Rhine between Worms and Bonn. 



The breadth of all the rings was measured and recorded 

 against the years in which they grew. A considerable agreement in 

 the growth was found in contiguous forests because that what the 

 trees register depends on their Situation. For instance trees on the 

 lake border are more independent on the quantity of rain. The 

 results represent approximately the tree growth for an area about 

 equal to i/^ part of Holland and are the following. 



The very considerable fiuctuations w^hich appear in the yearly 

 growth of the oak wood of the investigated regions must in great 

 part be due to meteorological infiuences. The temperature has 

 generally speaking a very small infiuence, but for a part of the 

 materials at least, (Moselle trees) the rain falling in spring and 

 Summer is of the greatest inüuence. In many cases, perhaps in all, 

 increased tree growth is not caused by the greater quantity of 

 rain directly, but indirectly through the greater height of the 

 subsoil water. 



In ever}?- year there was produced but one single growthring 

 at least ihis was the case in the last 70 years. If what seems 

 improbable the same thing does not hold in earlier years, then the 

 anomaly must have occurred everywhere at the same time. It 

 seems as if during pretty long intervals of time there is not only 

 a regularity but an actual pretty constant periodicity in the growth 

 of trees: showing a regulär fluctuation in 12,4 years during the 

 whole of the two last centuries. 



On the importance of this period the writer will not insist, as 

 he feels that it is still strongly in need of confirmation. He regards 

 California particular fitted for this brauch of research b}^ her very 

 old trees. Th. Weevers. 



Lange, A., Vinteren 1911 — 12 og dens Virkning paa 

 Havens Planter. [Der Winter 1911 — 12 und sein 

 Einfluss auf den Pflanzen des Gartens]. (Gartner-Tidende. 

 XXX. p. 28-30, 37—40, 42-43 und 50—52. 1914.) 



Nach einigen allgemeinen Bemerkungen über die Wirkung 

 der Kälte und des Frühjahr- Austrocknens der Pflanzen, beson- 

 ders der holzartigen Pflanzen, nebst einer kurzen meteorologischen 

 Uebersicht des betreffenden Winters, gibt der Verf. eine Liste von 



