February 12, 1886.] 



SCIENCE. 



151 



made by Dr. W. R. Miller, surgeon to the West 

 Riding convict prison. Dr. Miller experimented 

 on about four thousand prisoners for thirteen 

 years, and obtained results that differ sensibly 

 from those of Mr. Hansen ; for he found that the 

 season of maximum increase in weight in adults 

 is from- April to August, and the period of mini- 

 mum increase in adults from September to March. 

 Dr. Miller found the body became heavier in 

 summer, and lighter in winter ; and he attributes 

 the loss of weight to the more active excretion of 

 carbonic-acid gas in the colder months. 



DIFFERENT PHYSIOLOGICAL SENSES FOR 

 HEAT AND COLD. 



In connection with the researches of Professor 

 Hall and Dr. Donaldson of Johns Hopkins uni- 

 versity, recently given in Mind, it will be of 

 interest to state that Mr. A. Herzen has lately 

 published in the Archiv fur physiologie 1 the 

 results of a series of experiments showing that 

 the physiological sense of cold is different from 

 that of heat. His attention was first directed to 

 the subject by a simple incident, the verification 

 of which may be readily made by any observer. 

 Awakening one night, he found one of his arms 

 lying without the bed-clothes, ' alseep ; ' in touch- 

 ing it with the other hand, he perceived a distinct 

 sensibility to warmth, while that of touch was 

 gone. Bringing iiis arm, however, in contact with 

 cold substances, he was surprised to find no sensa- 

 tion. 



Pursuing the subject further, he produced arti- 

 ficially this condition of semi-paralysis by the com- 

 pression of ne-ve-trunks, and by experimentation 

 discovered that the sensibility to cold remained a 

 short time after tactile impressions had disap- 

 peared, and that the sensibility to warmth re- 

 mained much longer, but not quite as long as the 

 power of detecting pain ; also that the impressions of 

 warmth require more time for transmission to the 

 brain than those of cold, bearing, in fact, the same 

 relations to each other as the sense of pain does to 

 that of cold. These results were further supple- 

 mented by observations on a person with complete 

 and permanent tactile anaesthesia of the legs, but 

 in whom the sense of pain remained normal. The 

 subject was able to distinguish quite well the 

 differences in temperature between 150° F. and 

 81° F., which was the normal temperature of the 

 surface of the leg. Below the latter temperature, 

 however, no sensation was produced, not even by 

 the contact of ice on the inner side of the thigh. 

 Other cases showed the same peculiarities, in which, 



1 Ueber die spaltung des temperatursinnes in zwei geson- 

 derte sinne, xxxviii. p. 93, December, 1885. 



with the disappearance of tactile sensibility, the 

 susceptibility to cold was also lost, while that to 

 warmth yet remained. 



Vivisection experiments upon cats and dogs 

 lead the author to the following conclusions : 1. 

 The so-called sense of heat and cold is composed 

 in reality of two senses quite independent both 

 anatomically and physiologically : 2. Observations 

 on healthy and diseased subjects show that the 

 sensations of heat and cold are transmitted 

 through different nerves, by different routes, and 

 to different brain-centres ; 3. The gyrus sig- 

 moideus contains the centre (or the centripetal 

 branches leading thereto) of touch and cold percep- 

 tions ; 4. These sense-perceptions are transmitted 

 through the posterior columns of the. spinal cord, 

 while those of the senses of pain and warmth are 

 conveyed through the gray substance. 



Although the senses of cold and touch on the one 

 hand, and heat and pain on the other, seem to be 

 more nearly related, yet one cannot unite them, 

 or consider the different perceptibilities of heat 

 and cold mere modifications of those of touch 

 and heat. The researches of Blix and others 

 have demonstrated the existence of separated, 

 isolated, irregularly distributed points upon the 

 body, of which one may be only sensible to cold, 

 another to warmth, and a third to touch. Doubt- 

 less most persons have noticed the different de- 

 grees of susceptibility of different parts of the 

 body to heat and cold : the author points out 

 striking examples of such. 



RAINFALL IN SOUTH AFRICA. 1 

 Little has been known until recently on the 

 subject of rainfall in South Africa, taken broadly 

 over the whole country, although observers have 

 for many years been keeping records at isolated 

 stations. There has been for many years a meteor- 

 ological commission in existence at Cape Town ; 

 and in the report for 1883 an interesting table was 

 published, giving the means, monthly and yearly, 

 at all stations where records have been kept for at 

 least five years, with the altitude above sea-level, 

 and the latitude and longitude for each station. 



From these data Mr. Tripp has prepared a map 

 of South Africa, with the idea of showing the dis- 

 tribution of the total yearly rainfall. The curves 

 divide the area into districts, wheie the mean 

 yearly rainfall is — 



(1) Under 5 inches. 



(2) From 5 " to 10 inches. 



(3) " 10 " " 20 " 



(4) * 20 »• " 3 J " 



(5) Above 30 " 



There are doubtless, particularly along the moun- 



1 Abstract of an article by William B. Tripp, in Symons's 

 meteorological magazine. 



