58 



NATURE 



[July 8, 1909 



1-8, which fell subsequently to a point lower than that 

 with either endotoxin. Estimations of the opsonic indexes 

 made with the recently isolated strain gave results higher 

 than those obtained using the old strain. With another 

 endotoxin, varying doses (oi, ooi, and o-ooi mgrm.) all 

 produced marked rise in the opsonic indexes, the rise corre- 

 sponding with the dose, (c) Tubercle Endotoxin. — Injection 

 of 0002 mgrm. of endotoxin caused a rise in the opsonic 

 index to i-g sixteen days after. A similar dose of German 

 tuberculin R. produced hardly any effect. A large dose 

 (i-o mgrm.) of endotoxin caused a marked negative phase 

 (index 0-5) forty-eight hours after injection, with a sub- 

 sequent rise to i-8. Endotoxin (i-o mgrm.) prepared from 

 tubercle bacilli previously extracted with ether also pro- 

 duced a negative phase, with a subsequent rise to 1-5. 

 (d) Keeping Power of Endotoxin Solutions. — Experiments 

 were performed with staphylococcus and tubercle endotoxin 

 solutions which had been kept for seven weeks after pre- 

 paration ; there was little diminution in activity. Other 

 experiments indicate that the solutions deteriorate but little 

 for three to six months after preparation, (e) " Negative 

 Phase." — Experiments indicate that endotoxin produces 

 decidedly less " negative phase " than a vaccine. — The 

 occurrence of protandric hermaphroditism in Crepidula 

 fornicata : J. H. Orton. Crepidula fornicata is a 

 streptoneurous gastropod belonging to the family Calvp- 

 tneida'. Individuals of this species associate together 

 permanently in linear series, forming " chains." The 

 chains may consist of from two to twelve individuals. The 

 sex relations of the individuals were noted in about 300 

 chains. It was found that the individuals which occur 

 at the attached ends of the chains are always females, 

 those occurring near the top of the chains are males, while 

 those about the middle often possess the secondary sexual 

 characters of both sexes. In intermediate positions in the 

 chains occur forms which, in their secondary sexual 

 characters, are intermediate between females and herma- 

 phrodites on the one hand, and between hermaphrodites 

 and males on the other. Thus the chains present a tran- 

 sitional series, beginning with the males, which are the 

 youngest individuals, and ending with the females, which 

 are the oldest individuals. Microscopical examination of 

 the gonad has shown that there is as complete a tran- 

 sitional series in the primary sexual characters as occurs 

 in the secondary ones. All the adults are sedentary, but 

 the young are able to move about freelv. One thousand 

 young ones have been examined, and found to be all males. 

 There is, therefore, no doubt that all the individuals begin 

 life as males, and change gradually in the course of their 

 life-history into females. It is highly probable, from known 

 descriptions of allied species, and from observation on 

 species of allied genera, that protandric hermaphroditism 

 is common in the Calyptraeid.-p. Further, it seems probable 

 that the family will present a series in the evolution of 

 protandric hermaphroditism. If such a series be found 

 there is little doubt that a study of the earlier stages would 

 lead to the discovery of the nature of the sexes, i.e. in 

 Mendelian terms, whether the male is heterozygous and 

 the female homozygous, or vice vcrs6. Ten other strepto- 

 neurous hermaphrodites are known. It would seem, there- 

 fore, that one of the chief distinctions between the Streplo- 

 neura and the Euthyneura is beginning to break down.— 

 Sensitive micro-balances, and a new method of weighing 

 minute quantities : B. D. Steele and K. Grant.— The 

 polarisation of secondary 7 ravs : Dr. R. D. Kleeman.— 

 The absorption of homogeneous $ ravs bv matter, and on 

 the variation of the absorption of the rays with velocity: 

 W. Wilson. The experiments were made'with the view of 

 determining the manner in which the absorption coeflicient 

 of the rays varies with the velocity. Radium, which 

 gives out rays the velocities of which vary between very 

 wide limits, was used as a source of radiation. A beam of 

 rays from the radium passed into a magnetic field, by 

 means of which approximately homogeneous rays could be 

 brought into an electroscope." The velocities of the rays 

 could he determined from the streneth of the magnetic 

 field. Screens of metal of different thicknesses were 'inter- 

 nosed in the path of the rays, and it was found that the 

 •iw of absorption was not exponential, but approximately 

 linear, except for large thicknesses of absorbing material. 

 V arious experiments were made to show that this was not 

 NO. 2071, VOL. 81] 



due to the experimental arrangement, but was a real effect. 

 The fact that the /3 rays from uranium, actinium, &c., 

 are absorbed by matter according to an e.xponential law is 

 shown to be a proof, not of their homogeneity, but of 

 their heterogeneity. Groups of rays can be built up which 

 represent the properties of these rays with respect to 

 absorption. Further experiments were made on the change 

 of velocity of the rays after passing through absorbing 

 material, and it was found that the velocity of the rays, 

 contrary to the view expressed by H. W. Schmidt, is 

 appreciably reduced as they penetrate matter. The law of 

 absorption of the /3 particles when measured by the ionisa- 

 tion method involves a considerable number of factors, 

 and, as might be expected, no simple relation could be 

 found between the absorption of the rays and their velocity. 

 — Experimental researches on vegetable assimilation and 

 respiration ; v., a critical examination of Sachs' method 

 for using increase of dry weight as a measure of carbon 

 dioxide assimilation in leaves : D. Thoday. — The reproduc- 

 tion and early development of Laminaria digitata and 

 Laminaria saccharina : G. H. Drew. The processes of 

 reproduction and early development in both L. digitata 

 and L. saccharina are very similar. The plant is the 

 garrtetophyte, and is monoecious. The reproductive areas 

 occur as dark patches on the lamina, and consist of 

 gametangia embedded among paraphyses. The gametangia 

 contain small spherical gametes, 0.003 "t^i. in diameter, 

 and a number of globules of an oily substance. When 

 mature, the gametangia rupture at their distal extremity 

 and liberate their contents. The liberated gametes develop 

 two flagella of different lengths, which are inserted close 

 together ; they are phototactic, and move in the direction 

 of the longer flagellum. Cultures from the reproductive 

 areas were made in a culture solution consisting of various 

 salts dissolved in sea water. The solution was sterilised 

 by heat, and all flasks, pipettes, &c., were sterilised by 

 boiling. Division cultures containing the planogametes 

 were made, and eventually cultures free from growths of 

 the Ectocarpaceae and other algae were obtained. In such 

 cultures, stages of isogamous conjugation, resulting in a 

 spherical zygospore, were observed. Later a process grew 

 out from the zygospore, and expanded at its end, and then 

 the cell contents passed along this process, forming a 

 spherical mass at the expanded end. This became cut off 

 by a cell wall, and the remains of the zygospore de- 

 generated. The cell thus formed developed chromoplasts, 

 increased in size, and divided, producing typically a chain 

 of cells each having an outer and an inner cell wall. This 

 stage probably represents the sporophyte (2x) generation. 

 Any cell of the chain may then rupture its outer cell wall, 

 and by repeated divisions give rise to the laminaria plant 

 which emerges from the ruptured exosporium. The young 

 plant consists of a flattened lamina made up of cubical 

 cells, having at its base a number of colourless unicellular 

 rhizoids. The stipe is developed from the basal part of the 

 lamina. The disc-shaped expansion develops at the base 

 of the stipe and partially envelops the primary rhizoids ; 

 the hapteres arise as outgrowths from this disc. — The 

 germicidal action of metals, and its relation to the pro- 

 duction of peroxide of hydrogen : Dr. A. C. Rankin. — • 

 Surface flow in calcite : G. T. Beilby. — A preliminary note 

 on Trypanosoma ebcrthi (Kent) — {Spirochaeta eberthi, 

 Liihe), and some other parasitic forms from the intestine 

 of the fowl : C. H. Martin and Miss Muriel Robertson. 

 — The spectrum of magnesium hydride : Prof. A. Fowler. 

 The author has previously discovered that many of the 

 band lines peculiar to the sun-spot spectrum are identical 

 with lines composing the green fluting attributed to 

 magnesium hydride by Liveing and Dewar. The present 

 paper gives the results of a further investigation of this 

 spectrum with high dispersion, together with details of 

 wave-length determinations. The principal results may be 

 briefly summarised as follows : — (i) No sufficient reason 

 has been found for modifying Liveing and Dewar's con- 

 clusion that the spectrum is produced by the combination 

 of magnesium with hydrogen. (2) Lines are shown at 

 short intervals in all parts of the spectrum from the 

 extreme red to X 2300, and definite groups of flutings 

 begin at 5621 57, 5211.11, 4844-92, 4371-2, and near 2430. 

 (3) From photographs of the magnesium arc in hydrogen 

 at low pressures, taken with a lo-feet concave grating, the 



