March. 1911. 



KNOWLEDGE. 



Ill 



E. LEIT/ (LONDON) .A. N I) K. WINKEL 

 IGOTTINGEN).— We have received from E. Leitz 

 (London), Catalogues Nos. 7 and 8, devoted to photomicro- 

 graphic apparatus, and projection apparatus and drawing 

 appliances involving the principle of projection. These 

 catalogues give details of new apparatus specially designed to 

 meet the most recent requirements. In this connection 

 attention may be drawn to the photomicrographic apparatus 

 as suggested by Professor Hermann for taking photographs 

 of insects. .A.s an appendi.x to the list No. 7 there are two 

 plates of reproductions of actual photographs taken with the 

 objectives and apparatus of E. Leitz. 



Messrs. H. F. Angus & Co.. 83, Wigmore Street, W., have sent 

 us their new list of microscopes and accessory apparatus, by 

 K. W'inkel. Gcittingen, for whom they are acting as agents in 

 the L'nited Kingdom. The optical instruments of this firm 

 deserve to become better known amongst English workers, 

 and we can cordially recommend the intending purchaser of 

 a microscope to consider this list before coming to a decision. 

 The apparatus listed ranges from the simplest demonstration 

 instrument to that suited for the most exacting research. 



KOV.AL MICROSCOPICAL SOCIETY. January ISth. 

 1911. — Professor J. Arthur Thomson, F.R.S.E., President, 

 in the chair. — Mr. T. Chalkley Palmer made some remarks 

 upon a slide of Sitrirclla clegaiis, stained to show the 

 protoplasm which extended in unbroken continuity throughout 

 the tubes of the keels, where, by its streaming, it acted 

 through minute clefts upon the surroundings and moved the 

 diatom to and fro. The special point was that the mount 

 showed R. Lauterborn to be mistaken in assuming that 

 the streaming substance in the keels was gallerte or jelly. — 

 Professor J. Arthur Thomson, the retiring President, took as 

 the subject of his address " The Determination of Sex." 

 He discussed, historicallj- and critically, five theories or sets 

 of suggestions. 



(1) It has been suggested that environmental conditions 

 operating on the sexually-undetermined, developing offspring- 

 organism, may, at least, share in determining the sex. The 

 evidence in support of this has in great part crumbled before 

 criticism, and before the counter-evidence of cytologists and 

 Mendelians. But when we think of the gamut of life, we feel 

 it to be rash to exclude even this possibility. 



(2) It has been suggested that the sex is quite unpredestined 

 in the germ-cells before fertilisation, and that it is then settled 

 by the relative condition of the gametes (as affected by age, 

 vigtiur, and so on), or by a balancing of the inherited tendencies 

 which these gametes bear, neither ovum nor spermatozoon 

 being necessarily decisive. The evidence in support of this is 

 very far from satisfactory. Yet in view of some sets of experi- 

 ments, of R. Hertw-ig, in particular it seems rash to foreclose 

 the question. 



(3) It has been suggested that the sex is predestined at a 

 very early stage by the constitution of the germ-cells as such, 

 there being female-producing and male-producing germ-cells, 

 predetermined from the begimiing and arising independently 

 of environmental influence. The evidence in support of this is 

 \ery strong, both on experimental and on cytological grounds. 



(4) It has been suggested that maleness and femaleness are 

 Mendelian characters, and one form of this very attractive 

 theory is that femaleness is dominant over maleness, and that 

 females are heterozygous as regards sex, and males homo- 

 zygous as regards sex. But there are grave difficulties as well 

 as very striking corroborations. 



(5) It has been suggested that environmental and functional 

 influences, operating through the parent, (or, in short, the 

 parent's acquired peculiarities), may alter the proportion of 

 effective female-producing and male-producing germ-cells. 

 See, for instance, Russo's experiments on rabbits. This 

 possibility remains tenable. 



(6) It is suggested that there is no sex-determinant at all in 

 the usual sense, but that what determines the sex of the off- 

 spring is a metabolism-rhythm, a relation between anabolism 

 and katabolism. or a relation between the nucleoplasm and the 

 cytoplasm. Many sets of facts converge in the inference that 

 each sex-cell or gamete has a complete equipment of both 



mascuhue and feminine characters — of which there are doubt- 

 less chromosomic determinants. It may be that the liberating 

 stimulus which calls the masculine or the feminine set into 

 expression or development is afforded by the metabolism- 

 rhythm set up in the cytoplasmic field of operations. It may 

 be that this metabolism-relation — between nucleoplasm and 

 cytoplasm, doubtless, and likewise between anabolism and 

 katabolism — leads first and necessarily to tlie establishment 

 of ovaries or of spermaries, and secondly, either directly, or 

 through the gonads with their internal secretions, to the 

 expression of the contrasted masculine or feminine characters. 



(71 This interesting problem still implies a study of un- 

 certainties. But some progress has been made in the last 

 quarter of a century, and especially of late. Three general 

 impressions stand out clearly: (1) That the main steps of 

 progress have rewarded the cooperation of several distinct 

 methods; (2) That the variety of organisms is so great that 

 we should be very slow to argue dogmatically that what holds 

 good in one set must hold good all round; and (3) That what 

 is especially necessary on the part of biologists (according to 

 their opportunities) is a thatigc Skcpsis, — until we arrive at 

 secure conclusions. 



This being the .Annual Meeting of the Society, the following 

 Fellows were elected as Officers and Council for the ensuing 

 year : — 



President, H. G. Plimmer, F.R.S. — Vice-presidents. A. N. 

 Disney, R. G. Hebb, E. Heron-.AUen, J. Arthur Thomson. — 

 Treasurer, Wynne E. Baxter. — Secretaries, J. W. H. Eyre, 

 F. Shillington Scales. — Members of the Council, F. W. W. 

 Baker. J. E. Barnard. F. J. Cheshire. C. L. Curties, C. F. 

 Hill, J. Hopkinson. P. E. Radley, J. Rheinberg, C. F. 

 Ronsselet. D. J. Scourfield, E. J. Spitta, Sir .Almroth E. 

 Wright. — Librai'ian. P. E. Radley. — Curator of Instruments, 

 C. F. Rousselet. — Curator of Slides, F. Shillington Scales. 



ALGA FROM THE SEYCHELLES ISLANDS.— A friend 

 at the Quekett Microscopical Club recently gave me some 

 specimens of an Alga from the Seychelles. Definite informa- 

 tion was not procurable as to its e.xact habitat, but it was 

 believed to be marine and to occur on rocks on the sea shore. 

 Examination under the microscope leaves little doubt that it 

 should be classed with the Lyngbyeae. It does not appear to 

 correspond exactly with a recorded British species and 

 certainly not with any from fresh water. It consists of 

 unbranched filaments of considerable length ; these are 



A... 



composed of a somewhat thick-walled and strong sheath-like 

 tube, inside which are discs of protoplasm, normally packed 

 closely together ; they are without individual cell walls and 

 are. in the specimens given to me (preserved in formalin), of a 

 pale olive green, and are somewhat granular in appearance. 

 Figure 4, A. In what seems to be the young but mature 

 condition these fill the tube, but later they show a tendency 

 to cling together in rouleaux of six or more. Probably these 

 are " hormogones," the non-sexual reproductive bodies of 

 *he order. They would emerge from the tube, and being 

 disseminated in the water, develop into new filaments. The 

 discs are lenticular, somewhat thicker in the centre than 

 towards the periphery (Figure B, face view). When packed 



