254 



NATURE 



[January 12, 1893 



pyriform (more pointed at one end than the other) in birds 

 which, like the guiHemot, often change their position, sometimes 

 swimming and diving, sometimes perching on rocks, &c. An 

 examination of all the eggs in the zoological collection of the 

 St. Petersburg University fully bore out these views. Dr. Nicol- 

 sky thinks it would be useful to test the theory by experimenta- 

 tion, birds being kept in a vertical or horizontal position at the 

 laying time. 



For twelve years (1878 to 1890) M. P. Plantamour made care- 

 ful observations of the displacements shown by two spirit levels 

 (one north-south, the other east- west), in the cellar of his house at 

 Secheron. The instruments were transferred to the Geneva Obser- 

 vatory, and the work resumed by M. Pidoux in April 1891 (after 

 six months' interruption). M. Plantamour found that the mean 

 air temperature had a preponderating influence in the oscilla- 

 tions observed, while some other factors of obscure nature were 

 involved. The first year's data at Geneva {Arch, de Sci. ) reveal an 

 annual oscillation of the ground of the Observatory about an axis 

 directed north-east and south-west, such that the south-east part 

 sinks in summer and rises in winter. The east side went down till 

 July 16, then rose gradually till the end of December (29), there- 

 after sinking again. The extremes were — 4"73 and +4" '85 (an 

 amplitude of 9"'S8). The variations of the south side were 

 similar, but the amplitude somewhat greater. The north-south 

 level showed some quite abnormal variations in the autumn of 

 189 1, to which, however, the author does not attach great 

 importance. 



An interesting contribution to our knowledge of the adapta- 

 tion of structure to function in the human body is afforded in an 

 investigation by Signor Minervini (of the Naples Society of 

 Naturalists) of the blood-vessels of the skin in different parts. 

 Portions of skin were prepared so as to show the exact structure 

 of the chief arteries in them. The results are as follows: — 

 (i) The artery- walls of the skin in men are generally thicker than 

 those of other organs. (2) This greater thickness is due gene- 

 rally, and during most of life, to thickening of the middle 

 layer ; but in childhood the outer, and in advanced years the 

 innermost, layer is most developed. (3) The artery-walls in 

 the hollow of the hand, the finger-tips, and the sole, are, other 

 things equal, thicker than those in the back of the hand, the 

 forehead, the arm, &c. This greater thickness is due chiefly to 

 a greater development of the middle layer, and in all ages of 

 life. The arteries in the hollow of the hand in the case of 

 occupations involving hard manual labour show a greater in- 

 crease of thickness than in the case of those with little or no 

 such work. In these cases all three layers of the artery are 

 thickened, but the middle layer most. (4) In women all the 

 chief arteries of the hollow of the hand and of the back of the 

 hand are somewhat less thick than in men. The difference is 

 not great, but occurs at all ages. 



In a paper on the Santa Isabel Nitrate Works, Toca Chile, 

 read lately before the Scottish Institution of Engineers and 

 Shipbuilders, and now printed in the Institution's Transac- 

 tions, Mr. G. M, Hunter has something to say regarding the 

 origin of "caliche," as nitrate of soda is called in its native 

 state. Some contend that " caliche " is a marine deposit, others 

 that it is an anknal deposit, while others say it is a vegetable 

 deposit. Mr. Hunter holds the first of these views. The coast 

 of Chile has several times been disturbed and upheaved by 

 volcanic agency, and he suggests that a large tract of sea was 

 enclosed and heaved up to the present height of the nitrate 

 region, and there formed .in inland sea, which, after a lapse of 

 time under a tropical sun, evaporated, leaving the salts to per- 

 colate and form the beds of nitrate. From the formation of 

 the ground, showing depressions and ravines leading to the sea, 

 it is evident that immense volumes of water at some remote 

 period have passed through them. In proof of this, Mr 

 NO. I 2 II, VOL. 47] 



Hunter points out that no " caliche " is ever found in such 

 places, the accepted opinion being that there has been a "wash 

 out," as it is called. During a later period than that of the 

 formation of the "caliche" great floods passed over the plains, 

 as is shown by the deep tracks of rivers, and the smooth washed 

 appearance of the surface. Such periodical floods are common, 

 in tropical, rainless regions, and would not call for special 

 remark, but from the fact that wherever these river tracks or 

 washed surface appear no " caliche " can be found. This is so- 

 well known that even the workmen never attempt to search for 

 it in such places. The only surface indication for the presence 

 of "caliche " is rising ground covered with small black stones. 

 The "caliche" in its native state is white, very compact and 

 amorphous, not unlike rock salt, but when rich in iodine it 

 assumes various colours, according to the composition and 

 quality of the iodine it contains. For example, at times it 

 contains masses of bright yellow, red, or blue, and again wholly 

 composed of a dull black colour, in which state it requires arv 

 expert to distinguish it from costra or rock. 



Mr. E. Lommel claims to have found a simple explanation, 

 of the Hall effect. A simple train of reasoning shows, he says, 

 that the equipotential lines perpendicular to the lines of flow in 

 a plate are also the lines of force due to the current. If iron, 

 filings are strewn upon the plate they will arrange themselves 

 along the equipotential lines if the current be strong enough. 

 On bringing the plate into a magnetic field these lines of force 

 change their position. Hence the lines of flow, necessarily 

 orthogonal to the lines of force, will also change in form and 

 position. 



According to Dr. J. Bohm, the statement that Phytophthora 

 infestans, the fungus which causes the potatoe diseases, hiber- 

 nates in the tubers, is incorrect, nothing whatever being known 

 about its mode of hibernation. He further states that the infec 

 tion of the potatoes never takes place in the soil through the 

 uninjured skin, but is always brought about through injury to 

 the tubers by insects or snails. In potatoe- heaps sound tubers 

 can never be infected by their diseased neighbours. An infected 

 potatoe either does not germinate at all or produces a healthy 

 plant. 



In examining milk which is suspected to contain the tubercle 

 bacillus it is usual to subject a sample of the milk to the action 

 of a centrifugal machine after separating the fat. One method 

 of working is described by Ilkewitsch {Miinchener med. 

 Wochenschr. 1892). The casein in 20 c.c. of milk is coagulated 

 with citric acid, and, after filtering, the residue is dissolved in a 

 solution ofsodium phosphate. The butter-fat is separated by 

 shaking with 6 c.c. of an aqueous ether solution, and acetic acid 

 is then added until the liquid is on the point of coagulating. It 

 is then placed in a copper tube tapering at the bottom, and this 

 tube is inserted in the centrifugal machine and turned at the 

 rate of 3600 revolutions per minute for fifteen minutes. The 

 bacilli collect at the narrow end of the tube together with other 

 sediment and dirt. The liquid is poured off, and the sediment 

 examined microscopically. Thorner {Chem. Ztg, 1892, pp. 

 791-2) gives another method, which is as follows: — 20 c.c. of 

 the suspected milk are mixed with i c.c. of 50 per cent, potash 

 solution, and heated in a bath of boiling water until the fat is 

 saponified, when the solution turns yellowish brown. By this^ 

 treatment the casein and albumen become soluble in acid. 

 Twenty cubic centimetres of acetic acid are added, the solution 

 shaken, heated on water-bath for three minutes, transferred to a. 

 strong glass tube, and turned in the centrifugal machine for ten 

 minutes. The liquid is poured off, and the sediment is washed 

 by shaking with 30 c.c. hot water, and again turned in the 

 centrifugal machine. The water is poured off, and the sediment 

 placed upon cover-glasses, which are treated in the ordinary way,k 



