MISCELLANY, 



SOS 



becomes intensely heated. *' The quiver- 

 ing of the air over hot ground foreshadows 

 the whirlwind as mirage does the simoom, 

 and sultry heat and oppressive calm do the 

 hurricane." In the stratum of heated air 

 next the ground resides the energy which 

 produces the whirlwind. That this, in 

 many instances, is prevented from rising, 

 has been proved by numerous observations. 

 At last the upward tendency becomes so 

 strong that it breaks through the overlying 

 heavier air, and there occurs an upward dis- 

 charge, followed by all the phenomena of 

 whirlwinds. 



Dnpuy on the Fnactions of the Brain.— 



Dr. Eugene Dupuy, of Paris, has repeated 

 Terrier's experiments on the brain, with re- 

 sults which do not accord with those of the 

 English physiologist. In the Monthly for 

 December last we gave an account of Ter- 

 rier's researches, and hence it will suffice to 

 say here that in his experiments stimulation 

 of the superior external convolution of the 

 brain produced movement of the animal's 

 paw ; of the mid-frontal region, contraction 

 of the eyelid ; of the parietal region, move- 

 ment of the ear ; of the lower frontal and 

 orbital regions, movement of the tongue. 

 He therefore concludes that in these regions 

 there are actual centres for the movements 

 obtained. Dupuy, on the other hand, wher- 

 ever the electrodes were placed, whether on 

 the frontal, parietal, or orbital convolutions, 

 succeeded only in obtaining, on slight stimu- 

 lation, movements of the opposite fore-paw, 

 which, on stronger stimulation, extended to 

 the whole of that side of the body. Turther, 

 the electrodes applied to the uninjured sur- 

 face of the dura mater over the convolutions 

 produced the same effect as when placed on 

 the exposed convolutions themselves. 



Dupuy was led to suspect that the elec- 

 trical stimulation might in these cases be so 

 diflfused through the whole hemisphere as to 

 affect directly the base of the brain or even 

 the nerves arising there. To ascertain the 

 truth of this matter he laid bare one-half of 

 the brain of a dog, under complete anaBsthe- 

 sia, and applied to the posterior extremity of 

 the hemisphere the nerve of a galvanoscopic 

 frog, duly insulated. The electrodes were 

 then placed on the front of the hemisphere, 

 and movements produced in the opposite 



fore-paw, the legs of the frog beiug simul- 

 taneously thrown into violent contraction. 

 Upon another dog, under partial anaesthe- 

 sia, he divided the corpus striatum and optic 

 thalamus on one side, the corpus callosum 

 having previously been cut through. The 

 electrodes were then placed on the convolu- 

 tions above and behind the Sylvian fissure. 

 With a strong current, not only the fore-leg 

 of the opposite side, but also the hind-leg, 

 exhibited contraction. In another experi- 

 ment he removed the whole cerebral mass 

 above the pons YaroUi, and applied the elec- 

 trodes to the cut surfiice ; muscular contrac- 

 tions resulted, limited to the fore-limbs, right 

 and left. These results, many times ob- 

 tained, render it certain, according to Dr. Du- 

 puy, that electrical stimulation, to whatever 

 part of the brain it may be applied, is wide- 

 ly diffused ; and that such diffused stimula- 

 tion, reaching the base, and there affecting 

 the nuclei, the medulla, or the nerves them- 

 selves, will explain all the phenomena ob- 

 tained by Terrier and by himself on faradiz- 

 ing the convolutions. 



The Sponge-Fisheries. — The chief indus- 

 try of the Sporades Islands, in the Grecian 

 Archipelago, is the sponge - fishery. The 

 yearly average crop of sponges is estimated 

 at £120,000 sterling. The diving-appara- 

 tuses used in the fishery are imported exclu- 

 sively from England and Trance. Though 

 there is no difference in construction be- 

 tween English and Trench machines, with 

 regard to the depth they can attain, or the 

 length of time a diver can remain under 

 water, still English apparatus generally 

 proves stronger, and the gears are of supe- 

 rior quality. The air-tubes, however, have 

 hitherto labored under the disadvantage of 

 being heavier than the Trench, thus imped- 

 ing the free movements of the diver, the 

 tubes being caught among the rocks. But, 

 samples of Trench floating tubes having 

 been sent to England, the result has al- 

 ready been a great improvement in the 

 manufacture of the English article. A com- 

 mon fraud practised by traders in rough 

 sponges is to introduce into them a quan- 

 tity of sand, so as to add to their weight 

 In order to guard against this, agents are 

 now sent to Rhodes, which is the centre of 

 this commerce, to purchase the sponge 



