( ^23 ) 



floating period for separate fruit cones. I found, however, that the 

 floating period on a similar salt solution is so much greater for 

 fruitlets, which have been liberated from the cone (e. g. by dessication), 

 that the wide distribution now becomes quite intelligible, it' one but 

 supposes, that the germinative power is not damaged by a sojourn 

 of one month in sea-water. On this point, however, no experiments 

 have as vet, to my knowledge been made. Meanwhile 1 feel justified 

 in deducing' from the anatomical structure of the fruitlets, that 

 the embryo is most probably sufficiently protected against the entry 

 of sea-water. In some dotation experiments I found that after one 

 month HH)' n of the fruitlets of C. equisetifolia Forst., and upwards 

 of 75" of those of C. montana Jüngh. var. tenuior Miq. remained 

 floating. 



Besides by anemopliilous and hydrophilous distribution, C. equise- 

 tifolia and C. montana can spread by rootsuckers. The latter are 

 however rarely found in these species further than 10 m. from the 

 main trunk. Should the main trunk die off (for instance in conse- 

 quence of a fire) one can often observe, e.g. with C. montana, that 

 a young copse round the dead trunk has grown up from these root- 

 suckers. The distribution over very large intervals of sea. however, 

 no doubt takes place in Casuarina montana and C. equisetifolia by 

 means of the winged fruits, first through wind transport and then 

 through ocean currents. 



$ 5. On a monstrosity of Casuarina. 



In the Herbarium at Leiden I found a specimen, which had been 

 labelled by Boerlage as a monstrosity, collected by Junghuhn in Java 

 [in H. L. B. sub. n. 50 (899— 173) J. This malformation proved to 

 be a fruiting branch, resembling a witches' broom (in German 

 "Hexenbesen") and belonging to Casuarina montana var. tenuior 

 Miq. Besides the above mentioned aberrant mode of branching, this 

 specimen shows the peculiarity, that the axis of all its fruit cones 

 has continued to grow. The axis, thus continued, gives the charac- 

 teristic appearance to the shoots ; are these branched like a witches' 

 broom, have abnormally thickened internodes and bear abnormally 

 developed leafsheaths. The shoots in question also bore a small 

 number of normally formed young twigs and thus the determination 

 was possible to me. These normal branches, have regular cylindrical 

 internodes, about 1 cm. long and , — 1 mm. thick, generally with 

 11 vaginal teeth, as is often the case in the above variety. I was 

 unable to find a fungus or other cause for the formation of these 

 witches' brooms in the herbarium-specimen referred to. 



28 



Proceedings Royal Acad. Amsterdam. Vol. XI. 



