March 8, 1900] 



NATURE 



445 



We frequently also used a small shrimp trawl, but it was quite 

 ineffectual as far as Amphioxus was concerned. 



Two species of Amphioxus, Branchiostona belcheri and B. 

 cultellum, occur in the Malay Seas ; the latter is known from 

 Moreton Bay, Torres Straits and Celebes, while B. belcheri 

 has been hitherto recorded from Prince of Wales Islands, Torres 

 Straits, Borneo and South Japan, so that either of these species 

 might with equal probability have occurred at Singapore. 

 There is little of interest to note with regard to the specimens 

 themselves. Dr. Willey tells me that in the adult example the 

 "oral cirri are remarkable for the great size of the sense- papillae 

 which form long projecting conical processes." 



In the young, both before and after metamorphosis, the 

 dilation of the dorsal fin at a point vertically above the anus is 

 very marked (see woodcut). This feature has been noted by 

 Mr. Andrews in Japanese examples, and seems to be a point of 

 diflTerence from the specimens examined by Dr. Gilnther {v. 

 Zool. Anz. 18, 1895, P- 59)- In the diagram (Fig. i), which was 

 drawn from a preserved specimen, the notochord is curved up 

 dorsally at the posterior end. This seems to occur in all the 

 preserved examples I have examined, but it is certainly not 

 constant during life. F. P. Bedford. 



Zoological Laboratory, University College, W.C. 



Indian Corn. 



I THINK I can satisfy your correspondent, Mr. Kumagusu 

 Minakata (Nature, February 22, p. 392) about the " maize." I 

 have not Alhanasius Nikitin's travels before me, but I have 

 been over a good deal of his ground — and professionally in 

 charge of it — with the book in my pocket. 



We cannot now be sure what cereal he meant by " Indian 

 Corn." Probably the term includes several species of Indian 

 millets, great and small ; species of Holcus and Eleusine, 

 perhaps even rice. But Zea Alays, though well known 

 along Nikitin's line of march, is not a staple grain there even 

 now, though I understand it to be so used, to some extent, a 

 few degrees northwards. 



I do not think that any Anglo- Indian botanist will be found 

 to treat it as other than a Portuguese or Musalman importation 

 from the West. The natives certainly look upon it as an im- 

 ported plant ; like potatoes, tobacco, and several others. I sus- 

 pect that the native trivial name, Makd, implies that some 

 seeds may have been brought to India by pilgrims returning 

 from Arabia. 



As to Japan, that country is so much nearer to America, and 

 has so ancient a civilisation and commerce, that I should think 

 it very likely to have received American seeds of maize and 

 of other plants long before the Indian peninsula, though that 

 country is now full of Mexican and Peruvian plants — some 

 thoroughly naturalised — which have come " with the sun." 



At one time I thought that there were representations of 

 maize heads in the Ajanla caves, but I have had to give the idea 

 up, after examination on the spot. W. F. Sinclair. 



Chelsea, February 23. 



Colour of Horses for Service in Hot Countries. 



General Daumas, of the French Army, states in his book 

 on the horses of the Sahara that dark-coloured horses bear 

 great atmospheric heat much better than light-coloured horses. 

 I have had many opportunities in India of proving the correct- 

 ness of this observation ; but I have not been able to find a 

 correct explanation of this fact, and would therefore feel greatly 

 obliged if you or any of your readers would give me it. 



When the temperature of the surrounding air is much higher 

 than that of the animal body, the fact of a horse's coat being 

 dark would at first glance appear to be a disadvantage, be- 

 cause it would absorb heat faster than if it were light in 

 colour. Its power of radiation is evidently greater than that of 

 heat absorption. The colour of tropical animals, as we all 

 know, is darker than that of animals in colder climates. 



In speaking of light-coloured horses, I refer to the coat (hair) 

 and not to the skin. Absence of pigment in the skin appears 

 to decrease a horse's resistance to the effects of atmospheric 

 heat. Respecting this point, I have not sufficient data to make 

 any definite statement. M. H. Hayes, 



Rugby, March 3. 



NO. 1584. VOL. 61] 



An Interesting Case of Resonance. 



A CURIOUS example of resonance^is to be noticed in Llan- 

 dingat Church, Llandovery, South Wales. In one of the 

 windows there is a pane of glass which is not very tightly 

 fixed, being free to oscillate with a definite frequency, which 

 happens to correspond to the frequency of the low pedal " G " 

 of the organ. The consequence is that when the service is 

 taken in G, at the end of each of the Responses, Amens, &c., 

 quite a loud buzzing noise is produced by the resonance of the 

 window ; and I have seen strangers sitting near the window 

 seem quite perplexed, not knowing what causes the noise. 



Llandovery College, March 4. Kenneth McMurtrie. 



THE RELATION BETWEEN THE PERIODIC 

 CHANGES OF SOLAR ACTIVITY AND 

 THE EARTH'S MOTION. 



ONE of the most interesting questions arising from 

 the problem of the sun's activity is that of a possible 

 connection between the varying display of forces on the 

 solar surface and certain phenomena on our planet. The 

 evidence which has been gradually accumulating can 

 hardly fail to convince us of the existence of an inti- 

 mate, though still mysterious, relation between some of 

 the manifestations of the earth's magnetic forces and the 

 state of dynamic action on the sun. Not only the extra- 

 ordinary coincidences repeatedly recorded between solar 

 eruptions and terrestrial magnetic storms, but still more 

 the striking synchronism between the varying frequency 

 of solar spots and the observed changes in the display 

 of aurora;, and in the daily oscillations of the magnetic 

 needle clearly point to that conclusion. Scarcely less 

 certain seems to be the fact, confirmed by many recent 

 investigations, that a greater or less disturbance of the 

 sun's surface is attended by corresponding effects upon 

 terrestrial temperature, rainfall, and other meteorological 

 phenomena. 



But there appears to me to be good reason for be- 

 lieving that the influence of the solar activity upon our 

 planet is of an even more profound and far-reaching 

 nature than has hitherto been imagined. I shall en- 

 deavour here to state as briefly as possible the results of 

 investigations (more fully developed in Astr. JSlachr. No. 

 3619) which have led me to conclude that the period of 

 solar activity can be distinctly traced in the minute resi- 

 duals which it has not hitherto been possible to eliminate 

 from the observed values of the earth's elements. We 

 are thereby led to infer that the same unknown force 

 which apparently plays so important a part in the meteor- 

 ology of the sun, acts upon the motion of the earth to 

 such a degree as to produce perturbations which, though 

 minute, are yet of considerable importance from a 

 theoretical and even practical point of view. 



As regards the variation of the spot-phenomenon, all 

 the material here required could be taken from WoIPs 

 Astronoinische Miiiheilungen. The chief results which 

 we owe to the never-tiring zeal of this eminent astronomer, 

 and to his intense devotion to this particular branch of 

 astronomical science, are too well known to require, for 

 our present purpose, more than the remark that there 

 are two well-defined periods in the spot development, the 

 shorter embracing, on an average, about eleven years, 

 and the longer covering, in Wolfs opinion, nearly six 

 times that interval. These two periods are equally im- 

 portant for the following investigation, the curves of the 

 residuals showing the influence of the greater cycle not 

 less distinctly than that of the shorter one. To mention 

 some of the principal features of the " great " spot period — 

 this being probably less familiar to men of science than the 

 eleven years cycle— it may be stated that this curve rises 

 from a miniinum near the middle of last century to a high 

 maximum in 1783, then rapidly descends to a low mini- 

 mum in 1816, attains subsequently another high maximum 

 in 1838, descends again to a moderate minimum in 1861 



