48 SUMMARY OF CURRENT RESEARCHES RELATING TO 



P. muricata, P. contorta, and P. chihuahuana, and refers to the explana- 

 tion usually given as to the advantage of retention of the seeds until the 

 tree or branch is dead, in places liable to large forest fires. A brief 

 account is then given of experiments performed upon seeds of P. sero- 

 tina in June of the past year. The figures show that even in seeds 

 fourteen years old vitality was often retained ; in one experiment Gl 

 such seeds were planted and 21 germinated, while in another experiment 

 (57 seeds were planted and 11 germinated. The author draws attention 

 to the excellent conditions offered by closed cones for the preservation 

 of seeds, e.g. exclusion of spores of bacteria and fungi, maintenance of 

 requisite humidity, etc. 



Ferments and Latent Life of Resting Seeds.* — J. White has 

 studied the seeds of wheat, barley, and other cereals, and finds that they 

 contain diastatic, fibrin-digesting and ereptic ferments in appreciable 

 amount. The duration of the power of germination varies much, being 

 only about five years in rye, but eleven to sixteen years in wheat. The 

 ferments retain their activity for a long time after the power of germina- 

 tion has gone, sometimes for twenty years or more. A dry climate 

 favours the longevity of stored seeds. It is not possible to say whether 

 germination can take place in the absence of an enzyme, but no seeds 

 which had lost the power of germination could be made to germinate by 

 the addition of an enzyme, and where the germination was weak the 

 addition of an enzyme seemed to retard germination. Erepsin is more 

 abundant than pepsin, and is more abundant in rye than in any other 

 cereal ; it is almost absent in maize. After six hours' exposure to a 

 temperature of ',) ( J°-100° 0. vitality is destroyed, but the ferments are 

 unaffected. The latter are destroyed by one hour's exposure to a dry 

 heat at liJ0°-131° C. Diastase is most resistant to heat. Exposure to 

 liquid air may delay germination and decrease the percentage, but does 

 not kill the seeds or affect the ferments. The respiration of carbon- 

 dioxide by seeds stored in air when thoroughly dried, is inhibited when 

 the desiccation is only partial. 



New Flora of Krakatau.f— D. H. Campbell gives an interesting 

 description of the new flora of Krakatau. The latter, during the 

 volcanic outbreak of 1883, was covered with lava to the depth of 

 80 metres. At the suggestion of Treub, the island has been kept under 

 observation since 188G. In that year it was found that the Cyano- 

 phyceae had formed thin black films over the surface of the ashes, and 

 in this substratum several ferns and a few phanerogams had established 

 themselves. In 1897 the island was covered with a characteristic 

 vegetation — e.g. Ipomoea pes-aiprse, and other strand plants. There 

 were no trees and very few shrubs, but ferns predominated. The latest 

 expedition records that the present flora includes 187 species belonging 

 to all the principal groups. Ferns are no longer predominant, and the 

 forest vegetation is rapidly increasing, but there is a scarcity of Bryo- 

 phytes. A single specimen of Cycas rircimilis was found. 



* Proc. Roy. Soc, lxxxi. (1909) pp. 411-12. 

 t Amer. Nat., xliii. (1909) pp. 449-G0. 



