88 SUMMARY OF CURRENT RESEARCHES RELATING TO 



belonging to the Scandinavian flora, and describes the contrivance, not 

 hitherto noticed, in the aspen. 



Humboldtia laurifolia as a Myrmecophilous Plant.* — Prof. F. 0. 

 Bower's description of this plant, a native of Ceylon, is now published 

 in full. He ascribes the formation of the hollow channels in the stem 

 and branches which the ants inhabit in the first place to rupture from 

 tension ; and believes that the ants only then fortuitously take posses- 

 sion of them. He sees no evidence that the presence of the ants is of 

 any advantage to the plant. A somewhat similar structure occurs in 

 Clerodendron fistulosum n. sp. and Myristica myrmecopliila n. sp., and in 

 Nepenthes bicalcarata from North Borneo. 



Oxidation-process in Plants after death. — Herr J. Reinke f brings 

 forward experimental evidence, furnished by Herr G. Brenstein, that 

 after parts of plants have been completely killed by exposure for a 

 considerable time to an atmosphere saturated with vapour of ether, the 

 processes of oxidation and formation of carbonic acid still go on in 

 them ; and that this is dependent on temperature even more in the dead 

 than in the living plant. 



Herr W. Johannsen | objects to the validity of these experiments, 

 that they were made to extend over too long a period. These processes 

 cease on the death of the plant or part of the plant, but recommence 

 after a time under the influence of bacteria. True intramolecular respira- 

 tion will go on in an atmosphere destitute of oxygen, from the presence 

 of a fermentative substance, while " post-mortal " oxidation ceases at 

 once in such an atmosphere. 



Ketrogression in Oaks.§ — Herr F. Krasan has followed up his 

 previous " phyto-phylogenetic " studies by a study on the frequent 

 occurrence of abnormal leaves on oaks. The species studied was Quercus 

 sessiliflora Sm. His conclusions are as follows : — (1) The phenomena are 

 in origin pathological ; (2) the pathological state induces certain modes 

 of growth dormant in normal states; (3) but those structures which 

 develope symmetrically on affected branches and twigs, and unfold them- 

 selves uniformly, can no longer be called pathological. It seems very 

 probable (a) that the modes of growth evoked by the pathological state 

 are retrogressive. In previous generations the plant had followed 

 similar paths ; and indeed, in geological periods with warmer tempe- 

 rature, when the impulse which now evokes these " abnormal " leaves 

 in summer, was constant. (li) Q. aquatica Walt., in N. America, is 

 approximately in the state of the present Q. sessiliflora in the Miocene 

 age, when it was still Q. tephrodes Ung. (c) By the study of such 

 abnormal conditions much may be learned of phylogeny and relationship. 



Phenomenon analogous to Leaf-fall.|j — Mr. F. W. Oliver points out 

 that in Rubus austrcdis, a plant in which the lamina is supjjressed, the 

 leaves being reduced to simple mid-ribs of the leaflets, a layer of phellogen 

 is formed in the stem in the later part of the summer, out of the inner- 

 most of the cortical layers, all of which are assimilative. By this means 

 the rest of the assimilating cortex is cut off from the other tissues, and 



* Proc. Phil. Soc. Glasgow, xviii. (1887) pp. 320 -6 (1 pi.). Cf. this Journal, 

 1887, p. 785. f Ber. Deutsch. Bot. Gesell., v. (1887) pp. 216-20. 



X Bot. Ztg., xlv. (18S7) pp. 762-3. 

 § SB. K. K. Akad. Wiss. Wieu, xcv. (1887) pp. 31-42. 

 II Ann. of Bot.. i. (1887) pp. 71-2. 



