Biologie. — Morphologie etc. 355 



grandiflorus, sowie von Shorea stipiilaris experimentell zu ermitteln 

 indem er die Fallgeschwindigkeit beim Fall aus verschiedenen Höhen 

 mass. Er kommt zu dem Resultat, dass die beiden zu den Haupt- 

 flügeln ausgewachsenen Fruchtkelchzipfel bei den zwei geprüften 

 Dipterocnypus- Arien beim Reifabfali der schweren Früchte einen 

 genügend grossen Luftwiderstand ausüben, um mittelstarken Win- 

 den eine Verfrachtung auf Entfernungen zu ermöglichen welche 

 leicht 2—3 mal so gross und als die Höhe ihrer Geburtsstütte über 

 dem Boden beträgt. Die Versuche mit der schweren Frucht von 

 Shoven stipiilaris zeigten genügende Funktionsfähigkeit für die Aus- 

 nutzung des Luftwiderstandes nach dem Typus der Schraubendreh- 

 fliezer. Die Kantenflügcl von Dipterocarpus grandißoriis haben für 

 die Flugfähigkeit keine Bedeutung (wie sich aus dem Vergleich des 

 Verhaltens von unversehrten mit dem von amputierten ergab), des- 

 gleichen die drei aus Kelchzipfeln hervorgegangenen kleinen Flügel. 



Neger. 



Aflfourtit, M. F. A. and H. C. C. la Riviere. OntheRibbing 

 ofthe Seeds of Ginkgo. (Ann. Bot. XXIX. p. 591—595. 1 textfig. 

 1915.) 



The authors had the opportunity of examining a large number 

 of seeds from a specimen of this tree grown near Rotterdam. 

 They found marked Variation in the form of the stone. — 47 seeds 

 being 2-ribbed, 65, Sribbed and 5, 4-ribbed, and there were also 

 many transitional forms. The authors therefore agree with Oliver 

 and Salisbury (On the Structure and Afifinities of the Palaeozoic 

 Seeds of the Conostoma Group. Ann. Bot. Vol. XXV. 1911) that „The 

 facts seem to indicate that, whilst the terms „radiospermic" and 

 „platyspermic" have a definite use as morphological distinctions, 

 our attitude towards them as criteria of taxonomic importance may 

 require readjustment." Agnes Arber (Cambridge). 



Beer, R. and A. Arber. On the Occurrence ofBinucleate 

 and Multinucleate Cells in Growing Tissues. (Ann. Bot. 

 XXIX. p. 597, 598. 1915.) 



The authors' Observation have led them to the conclusion that, 

 in the case of the cortical and medullary parenchyma of stems, a 

 stage in which each cell generally contains more than one nucleus 

 often intervenes as a normal phase ofdevelopment between 

 the meristematic and mature conditions. This stage may be highly 

 protracted, or it may be so brief as to be easily overlooked. The 

 number of nuclei may be two, or many more. The ultimate fate 

 of the nuclei has not been fully worked out, but there are indica- 

 tions that in some cases fusions may occur at a later stage. The 

 total number of species in which a binucleate or multinucleate 

 phase has been observed is 76: these cases are nearly all Angio- 

 sperms but 2 species of Equisetiini and one species of Araucaria 

 are included. The plants examined ränge from trees to small an- 

 nual herbs; vegetative and reproductive axes have been chiefly 

 studied, but a few roots, leaves and cotyledons are included. In 2 

 roots, amitosis has been observed, but in the great majority of 

 cases the nuclei of the multinucleate cell arise by mitosis. There 

 are certain exceptional features connected with these mitoses and 

 ■with the behaviour of the associated cytoplasm. The most striking 



