December 23, 1909J 



NA TURE 



237 



frequently be demonstrated. (6) Concerning phagocytosis : 

 It would appear necessary to avoid mixing specimens of 

 normal or pathological blood, because just as samples of 

 sera are known to vary in value, so do the leucocytes, 

 although to a less extent, whether they are obtained from 

 specimens of normal or pathological blood. Still further, 

 by mixing samples of normal or pathological blood a 

 hemolytic action may be induced which in itself has been 

 found capable of exciting abnormal results in phagocytosis. 

 (7) It appears to be incorrect to regard a specimen of blood 

 as normal until it has been subjected to a detailed examina- 

 tion by the methods referred to in this and the two previous 

 communications, quite irrespective of its actual source 

 — L. Doncaster : Gametogenesis of the gallfly Neuroterus 

 Icnticiilaris (Spathegaster baccarum), part i. The cynipid 

 Neuroterus lenlicularis has two generations in the year, 

 hatching in April and June. The April generation con- 

 sists of females only, which lay parthenogenetic eggs. 

 Evidence is given that some of these flies lay only eggs 

 destined to become males, other flies only eggs which 

 become females. The June generation thus consists of 

 males and females ; the eggs are fertilised and give rise 

 to the generation which appears in April. In the sperma- 

 togenesis 10 chromosomes are found in the spermatogonial 

 mitoses. In the spermatocytes, the first maturation divi- 

 sion is abortive, only a small piece of cytoplasm with the 

 centrosome being separated. In the second spermatocyte 

 division 10 chromosomes appear and divide equally into 

 the spermatids. The two spermatids are similar, except 

 that one receives a small extra-nuclear body absent in tlip 

 other. Somatic mitoses in the male show 20 chromosomes, 

 except in the nerve-cells, which appear to contain 10 

 only. The eggs of the June generation undergo a double 

 but irregular maturation division, apparently leaving 10 

 chromosomes in the pronucleus. Segmentation divisions 

 in these eggs and body-cells in females of both genera- 

 tions show 20 chromosomes. The study of the matura- 

 tion of the eggs of the spring (parthenogenetic) generation 

 is not yet complete, but suggests that the eggs of some 

 females undergo maturation and chromosome-reduction ; 

 those of others undergo no reduction. It is suggested that 

 the former eggs yield males, the latter females. These 

 observations, combined with (i) those of the author on 

 the relation between sex and a somatic character in the 

 moth Abraxas, (2) with the inheritance of such cases as 

 colour-blindness, and (3) with the sex-relations of " hetero- 

 chromosomes " in insects, lead to a hypothesis as to the 

 nature of sex. It is suggested that there are male and 

 female sex-determinants (symbols (J, 9) which behave as 

 Mendelian characters, each being allelomorphic with its 

 absence (symbol l). Females have constitution 9 di and 

 produce 9 eggs and (S eggs ; males have constitution 

 i$ < I . and produce cJ and spermatozoa. 9 eggs are 

 fertilised by cJ spermatozoa, yielding females; cJ eggs by 

 G spermatozoa, yielding males. — Dr. E. Schuster : Pre- 

 liminary note upon the cell lamination of the cerebral 

 cortex of echidna, with an enumeration of the fibres in 

 the cranial nerves. — Dr. F. \V. Mott, Dr. E. Schuster, 

 and Prof. W. D. Halliburton : cortical lamination and 

 localisation in the brain of the marmoset. This research 

 is one which has been carried out on lines similar to that 

 previously published by two of the authors in relation to the 

 brain of the lemur. A series of sections of the cerebral cortex 

 has been examined in order to map out the extent and 

 boundaries of the types of cell lamination observed. It is 

 now well known that these differences are correlated with 

 differencr-s in function, and this method of histological 

 localisation of function (as it may be termed) has been 

 controlled by the physiological method of stimulation. — 

 R. H. Whitehouse : The caudal fin of fishes (preliminary 

 paper). The paper communicated is a summary of a fuller 

 work on the caudal fin of fishes in general, but principally 

 the Teleostei. It aims at a revision of the definitions of 

 terms in general use, in order to disperse the vagueness 

 surrounding these terms. Diphycercy is shown to be very 

 vague, inasmuch as it does not specify the primary or 

 secondary nature of the symmetry, and thus it may be 

 dispensed with in favour of protocercy and gephyrocercy, 

 the former of which implies primary, and the latter 

 secondary, symmetry. Concerning heterocercy, the essen- 

 tial features of this condition are considered to be (i) an 

 NO. 2095, VOL. 82] 



enlarged lower lobe, and (2) the retention of individual 

 centra, when formed, to the end of the axis. The term 

 " hypural " is introduced into this form, since there is 

 evidence of these structures being formed by the union of 

 radials and hajmal arches. Under homocercy, three 

 varieties of fin-structure are discussed for the purpose of 

 showing (i) the breadth of the term, (2) features which 

 determine the degree of specialisation, and (3) the taxo 

 nomic value of the caudal. Evidences of caudal abbrevia- 

 tion are reviewed, and a re-defining of the term " epural " 

 is given, by which this structure is considered the dorsal 

 homologue of the ventral hypural. The presence of radials 

 dorsally and ventrally is directed attention to, and also the 

 composite nature of hypurals and epurals. Finallv, 

 evidence is given in support of the theory that the per- 

 manent homocercal caudal is a shifted anal, and, moreover, 

 support is forthcoming among the Elasmobranchs. — H. E. 

 Arbuckle : Some experiments with the venom of Causus 

 rhombeatus.—Dr. V. H. Veley and Dr. A. D. Waller : 

 The comparative action of stovaine and cocaine as measured 

 by their direct effects upon the contractivity of isolated 

 muscle. As tested by an independent method, these two 

 drugs are found to be of approximately equal physiological 

 action in correspondence with their affinity values. — Sir 

 David Bruce, Captains A. E. Hamerton, H. R. Bate- 

 man, and F. P. Mackie : Glossina palpalis as a carrier 

 of Trypanosoma vivax in Uganda. — Prof. W. M. Hicks : 

 .■\ critical study of spectral series, part i., the alkalies, H 

 and He.— G. 'W. C. Kaye : The distribution of the 

 Rontgen rays from a focus bulb. A Rbntgen bulb was 

 constructed with an antikathode the inclination of which to 

 the beam of kathode rays could be varied at will. The 

 bulb as a whole was also capable of rotation, and thus by 

 the use of a stationary ionisation chamber, intensity dis- 

 tribution curves could be obtained for the X-rays. The 

 hardness and intensity of the Rontgen rays were found to 

 be almost independent of the obliquity of the antikathode. 

 Some possible improvements in the modern focus bulb are 

 suggested in the paper. — R. D. Kleeman : The direction 

 of motion of the electrons ejected by the a particle. When 

 an o particle collides with a molecule, we should expect 

 that the direction of motion of the ejected electron depends 

 on that of the a particle. If the whole or a part of the 

 energy of ionisations is derived from the a particle, the 

 electron should have a component of motion in the same 

 direction as the direction of motion of the a particle. 

 Some experiments to test thif showed that when o particles 

 are shot through thin metal foil more electrons are given 

 off from the side of the foil where the a particles emerge 

 than where they enter. This shows that the motion of 

 the liberated electrons is on the whole in the same direction 

 as that of the ionising a particle.— F. Soddy and A. J. 

 Berry : Conduction of heat through rarefied gases. By 

 the aid of the calcium absorption process of producing 

 high vacua, the conductivity of twelve gases for heat has 

 been determined at pressures so low that the actual path 

 of the molecule is comparable with its mean free path 

 (c/. Sir W. Crookes, Proc. Roy. Soc, 1880, 31, 239). 

 By an electrical method the heat dissipated from a platinum 

 strip, maintained at 61° in the gas, has been measured at 

 various pressures down to a thermally perfect vacuum. 

 As indicated by the kinetic theory, the heat dissipated at 

 low pressure is proportional to the pressure, whereas at 

 higher pressures it is independent of pressure. It was 

 found that the conductivity in the first case bore no relation 

 to that in the second. At all ordinary pressures hydrogen 

 and helium are easily the best conductors, while of the 

 gases examined carbon dioxide was the worst. At low 

 pressure the conductivity of acetylene, methane, and 

 cyanogen somewhat exceeded that of hydrogen, while 

 helium was but slightly better than carbon dioxide. At 

 low pressures the conductivity will be defined in terms of 

 the calories (x lo-'') dissipated per second, per 001 mm. 

 of pressure, per sq. cm. of surface, per 1° difference of 

 temperature between the surface and the wall of the con- 

 taining vessel. The symbols K and Q will be used to 

 express respectively the experimental and calculated values 

 of the conductivity so defined. On the assumption that the 

 heat interchange between the molecule and the surface it 

 impinges upon'is perfect, Q is the product of the number of 

 impacts of the molecules per second per sq. cm. and the 



