NA TURE 



[June 22, 1905 



course will be delivered in March and April, 1906, by 

 Prof. H. A. Lorentz, professor of physics in the University 

 of Leyden. 



Under the title " The Education of the Examiner," Dr. 

 Charles E. Fawsitt publishes, in the Proceedings of the 

 Royal Philosophical Society of Glasgow, an interesting 

 note on the statistics of examination marks as revealed by 

 graphic methods. Most examiners who have had to draw 

 curves showing the distribution of marks in any examin- 

 ation know the difficulty of obtaining an even uniform 

 curve rising continuously to a maximum and then descend- 

 ing continuously. However carefully the scale of marking 

 is adjusted, the curve has an unpleasant habit of showing 

 two maxima, usually of unequal height, instead of the one 

 maximum of the generally recognised standard curve. Dr. 

 Fawsitt, as the result of observations on class examin- 

 ations conducted at Edinburgh, brings forward the welcome 

 suggestion that this irregularity is not the fault of the 

 examiner, but is due to the fact that the candidates 

 naturally divide themselves into two sets, namely, workers 

 and non-workers, and that while the students in either set 

 vary in every conceivable way in respect of aiility, a 

 marked line of division is drawn with regard to work. 

 The superposition of two error curves, in accordance with 

 this theory, gives results closely agreeing with those of 

 common e.xperience. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, March 16. — " On the Dimorphism of the 

 English Species of Nummulites, and the Size of the Megalo- 

 sphere in relation to that of the Microspheric and Megalo- 

 spheric Tests in this Genus." By J. J. Lister, F.R.S. 



The results obtained in this investigation are summarised 

 as follows : — ■ 



(i) Both microspheric and megalospheric forms of 

 N. variolarius and N. Orbignyi var. elegans are present 

 in the Eocene beds of the Isle of Wight and Hampshire, 

 as the author believes they will be found to be present 

 elsewhere, except when the materials of a bed have been 

 re-arranged under the influence of currents. 



(2) In these species and in A'^. laevigatus and N. 

 gizehensis the size of the microsphere is nearly constant — 

 the diameters in the specimens measured being between 

 15 II and 20 n. 



(3) In the nine species and one variety of Nummulites 

 which the author has examined, the size of the megalo- 

 sphere is approximately proportional to the volume of the 

 contents of the microspheric form. 



By this result additional proof is given of de la Harpe's 

 conclusion, founded on the mode of occurrence in the beds, 

 and on structural features of the tests of the two forms! 

 that these are in each case truly members of " a pair," 

 or, as we now say, are related as alternating or recurring 

 forms in the life-history of a species. 



By (2) and (3) the two modes of reproduction come into 

 marked contrast, the asexually produced megalospheres 

 being proportional in size to the protoplasmic volume of 

 the parent, while the microsphere, probably arising as a 

 zygote, is uniformly small throughout. 



(4) In several of the species examined, as the micro- 

 spheric member of the cycle preponderates in the life- 

 history, the megalospheric (or gamete-producing) member 

 decreases, not only in proportion to the size of the micro- 

 spheric form, but in proportion to the megalospheric 

 members of other species in which the two forms attain 

 approximately equal sizes. 



April 6. — " Ovulation and Degeneration of Ova in the 

 Rabbit." Bv Walter Heape. Communicated by Adam 

 Sedgwick, F.R.S. 



This paper is an abstract of several vears' e.xperimental 

 work. The growth of the graafian vesicle and ovum, and 

 the modification of the adjoining ovarian tissue, are referred 

 to. The maturation of the ovum takes place in the ovary. 

 It IS dependent upon coition, and follows a cessation of 

 NO. i860, VOL. 72] 



the supplv of nutriment to the ovum. Ovulation occurs 

 ten hours after copulation, and does not occur if coition 

 is prevented. 



The cause of the rupture of the graafian vesicle is 

 probably due to the stimulation of ovarian contractile 

 tissue, to effect which, in the domestic rabbit, the excite- 

 ment of sexual contact appears to be necessary. 



The prevention of coition results in the degeneration of 

 ripe follicles, and the production of false corpora lutea. 

 Such degenerate follicles do not rupture, and the ovum 

 contained therein is not discharged. The structure and 

 fate of the true and false corpora lutea are briefly 

 described. 



The persistent prevention of breeding causes degener- 

 ation of young as well as ripe follicles on a large scale, 

 and results in more or less obstinate sterility. 



Degeneration of young follicles occurs normallv. While 

 this may be due to want of nutriment, caused by competi- 

 tion of neighbouring follicles, it may also be due to in- 

 capacity to assimilate the nutriment which is supplied. 



In this latter case, failure is due to a peculiarity in the 

 constitution of the ovum, constituting it a "sport." As 

 there is evidence that the production of variable offspring 

 depends upon the quality or quantity of nutriment supplied 

 to the mother, it is urged that the study of nutrition from 

 this point of view becomes a matter of very great interest 

 and importance to students of heredity. 



A brief review of the evidence concerning the forces 

 which influence breeding results in the conclusion that 

 changes are induced in the constitution of the blood by 

 means of a " generative ferment " of extraneous origin ; 

 the effect of which upon the generative glands causes their 

 secretion of "gonadin," which exercises a profound effect 

 upon the r^st of the generative system. 



" On the Nature of the Silver Reaction in Animal and 

 Vegetable Tissues." By Prof. A. B. Macallum. 



When fresh preparations of animal and vegetable tissues 

 are treated with a solution of nitrate of silver containing 

 free nitric acid and then exposed to light, they become 

 coloured, the colour varying in intensity and tint. The 

 author endeavoured to determine to what the reaction is 

 due, and how far one may go in employing it for micro- 

 chemical purposes. It was found that of the organic con- 

 stituents of tissues, the only ones which form compounds 

 with silver " reducible " under the action of light are 

 sulphocyanic acid, creatin, and taurin. As creatin is pre- 

 sent only in vertebrate muscle fibre, and not at all in 

 invertebrates, while the other compounds mentioned occur 

 in tissues only in infinitesimal, and, therefore, in negligible, 

 quantities, the silver reaction cannot be attributed to their 

 presence. It was further ascertained that neither phos- 

 phates, carbonates, nor sulphates give " reducible " silver 

 compounds in . the presence of free nitric acid. There re- 

 mained, among organic compounds in tissues, only the 

 proteids, and as these have been, and are, generally held 

 to form, with silver salts, compounds which are " reduced " 

 in light, it was necessary to determine whether the coloured 

 compounds so formed are " albuminates " or simply the 

 subchloride of silver. For this purpose proteids were freed 

 from chlorides by repeated precipitation with pure 

 ammonium sulphate, and it was found that egg and serum 

 albumins and globulins, as well as the gelatins, after the 

 eighth precipitation give no colour reaction whatever with 

 nitrate of silver under the influence of light, and that the 

 compounds eliminated by the precipitation, and to which 

 the silver reaction is due, are chlorides. Nucleo-proteids 

 also were found to be reactionless. In the case of vege- 

 table proteids the methods employed were different, but 

 the result was the same. Silver nitrate may, consequently, 

 be used as a microchemical reagent for determining the 

 presence of chlorides in animal and vegetable tissues, and 

 its use for this purpose has already furnished some im- 

 portant results, .'\mongst these may be mentioned the 

 absolute freedom of the nucleus from chlorides, the absence 

 of the latter from the head of the spermatozoon, and the 

 demonstration that they alone are the cause of the silver 

 reaction in the '• cement substance " (of von Reckling- 

 hausen) as well as in ordinary cell protoplasm. 



