590 



NATURE 



[December 29, 1921 



first visible indication of healing is the deposit of 

 fatty substances from the evaporating sap at the cut 

 surface and their later transformation into a resistant 

 substance of the nature of " suberin " or "cutin." 

 The nature and origin of the protective layer in the 

 exodermis of the root and the general distribution of 

 the endodermis and its frequent transition through 

 different structural stages are briefly described. 

 Primary and secondary stages have different pov^ers 

 of resistance to the entry of pathogenic organisms ; 

 the importance of these considerations in relation to 

 mycorhiza was indicated. After the cortical tissues 

 of the root are isolated from the vascular strand by 

 a secondary endodermis with suberin lamellae plus 

 casparian strip, fungi found penetrating cortical 

 tissues only may be regarded as saprophytic 

 rather than parasitic. In the stem the first line of 

 protection against pathogenic organisms lies in the 

 cuticle. Underground and submerged stems usually 

 possess a well-developed endodermis. In some 

 plants a functional endodermis, normally absent, can 

 be developed by etiolation, and its occurrence has a 

 profound influence on the structure of the plant. 

 After a wounded parenchymatous surface has been 

 blocked by the rapidly forming deposit of suberin 

 the tissues beneath usually give rise to an active 

 phellogen producing cork. The general principles 

 underlying cork formation and the occurrence of cork 

 in normal stems and roots are briefly reviewed. In 

 many cases the occurrence of deep-seated layers of 

 cork could be associated with their formation beneath 

 functional endodermal cylinders. 



Faraday Society, December 13.— Prof. A. W. Porter, 

 president, in the chair. — A. O. Rankine : The struc- 

 ture of some gaseous molecules of which hydrogen is 

 a constituent. Data relating to the viscosity of gases 

 the molecules of which contain one or more 

 hydrogen atoms provide means of obtaining some 

 knowledge of the dimensions of the molecules. An 

 examination of certain hydrogen compounds contain- 

 ing different numbers of hydrogen atoms leads to novel 

 views of the arrangement of the atoms. The be- 

 haviour of the molecules in molecular collision is 

 considered and tables are given of the "mean collision 

 areas." Assuming that the atoms towards the end 

 of each period of the periodic table are equal in size, 

 it is probable that as the number of hydrogen atoms 

 in the molecule increases their nuclei^ become more 

 remote from the nucleus of the central atom. The 

 retreat of the hydrogen nuclei is due to their mutual 

 repulsion, and the efl'ect eventually leads to the failure 

 to form such molecules as BH5 and AIH5. A com- 

 parison is made of the relative dimensions of CH^ 

 andl Kr, which prove to be of the same size to a 

 degree within that of experimental errors. The iden- 

 tity of correspondence between CH, and NH, as 

 compared with that between Kr and Rb, and the 

 equality of domains occupied in corresponding crystals 

 bv NH, and Rb respectively are indicated. Estimates 

 of molecular dimensions from viscosity measurements 

 agree with these results. 



Society of Glass Technology, December 14. Dr. 



Morris W. Travers, president, in the ■ chair.— 

 I. Masson, N. F. Gilbert, and H. Buckley : A suggested 

 method of investigating the viscosity of glass. Apply- 

 ing a modified form of Stokes's law to ocular measure- 

 ment of the rate of fall of a metal sphere in a vi'^cous 

 fluid gives results in fair agreement with the X-ray 

 measurement where the shadow of the sphere was 

 projected on to a photographic plate. For molten 

 glass alundum crucibles had been found satisfactory, 

 with platinum or large nickel balls. — V. Stott : Note 

 on pipettes. Pipettes should be adjusted for a par- 



NO. 2722, VOL. 108] 



ticular delivery time, and they are unsatisfactory if 

 the delivery time is too short or too long. A definite 

 period should be allowed for drainage when 

 graduating, testing, and using pipettes. — F. Twyman : 

 The annealing of glassware and annealing without 

 pyrometers. A piece of the glass to be annealed is intro- 

 duced into the furnace among the articles to be an- 

 nealed. It is elastically strained by a definite amount, 

 sufhcient stress being brought to bear to deform it. 

 Periodically the stress is removed. As the tempera- 

 ture of the furnace is raised a time will come when 

 the test-piece will not recover entirely, and from a 

 record of the time during which the piece has been 

 kept strained at a particular temperature and the extent 

 to which it recovers its original position it would be 

 possible to calculate the time of relaxation at the tem- 

 perature. For practical purposes if it springs back on re- 

 lease by one-half its originally strained amount it has 

 been half-annealed, and so on ; this time is indepen- 

 dent of whether the lehr has been kept at a constant 

 temperature during the annealing or not. If the test- 

 piece deliberately strained is annealed, then the other 

 objects which have passed through the same tempera- 

 ture and were originally strained by want of anneal- 

 ing will become annealed simultaneously to the same 

 degree. 



Linnean Society, December 15. — Dr. A. Smith Wood- 

 ward, president, in the chair. — F. A. Potts : The 

 work of the Carnegie Institution in the marine biology 

 of Samoa. The Island of Tutuila, its wooded cliffs, 

 coral-reefs, and the fish fauna, were described, with 

 illustrations taken under water. — G. C. Bourne : The 

 Raninidae, a study in carcinology. The Raninidae, 

 a family of the Decapoda Reptantia, have arisen in- 

 dependently from Astacuran ancestors. Although the 

 endophragmal skeleton of the Raninidae exhibits cer- 

 tain cancroid characters, it is much more nearly 

 related to the macruran than to the bachyuran type. 

 The "epistome" is the antennary s4:ernum, and the 

 mandibular sternum enters into the composition of 

 the preoral ventral plate. It is proposed to place the 

 Raninidae in a separate tribe, Gymnopleura, defined 

 as follows : — Anterior thoracic sterna broad, posterior 

 sterna narrow and keel-like ; posterior thoracic 

 epimera largely exposed by reduction of the branchio- 

 stegite ; female openings on coxEe ; last pair of pareio- 

 pods dorsal in position, normal or reduced in size. 

 Sternal canal present ; thoracic nerve ganglion-chain 

 elongate ; antennary sternum triangular, spout-shaped ; 

 branchia 8 on each side. The respiratory mechanisms 

 of the Raninidae were described. The antennary 

 flagella are usually short, but there are special ar- 

 rangements for maintaining a respiratory current of 

 water when the animals are covered with sand or 

 mud, for they are burrowers ; Notosceles shows 

 adaptations to a swimming habit. 



Dublin. 

 Roval Dublin Society, December 20. — Mr. G. Fletcher 

 in the chair.— H. H. Dixon and N. G. Ball : Photo- 

 synthesis and the electronic theory, ii. Experiments 

 were described showing that the sensitisation of photo- 

 graphic films to red light by chlorophyll and by a 

 commercial sensitiser is efi"ective at the temperature 

 of liquid air. It has been previously shown that 

 chlorophyll does not emit electrons when exposed to 

 visible light in sufficient number to account for photo- 

 synthesis ; hence the present experiments indicate that 

 the effect of light is to cause a displacement of elec- 

 trons within the chlorophyll molecule, thus rendering 

 part of the molecule reactive. A new scheme of 

 photosynthesis is suggested.— P. A. Murphy : The 

 bionornics of the conidia of Phytophthora iufesfans. 



