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THE POPULAR SCIENCE MONTHLY. 



think that success in this sphere of action 

 merely indicated that the prize-man had 

 the ability and skill to get on in an exami- 

 nation. No doubt a stupid and idle man 

 could not get first places in examinations, 

 and so the industrious and clever were 

 picked out by the process. But it was cer- 

 tainly not the case that those who failed to 

 get the highest honors in examinations went 

 to the wall in after-life. On the contrary, 

 he was sorry to say that he knew some who 

 had succeeded to the fullest extent during 

 the examinational period of their life, yet 

 did not maintain their prestige as time rolled 

 on. And not a few men who were signal 

 failures at examinations have proved of 

 enoi-mous value in after-years. To some a 

 vast amount of evil was wrought from the 

 fact that no proper knowledge had been ac- 

 quired to pass the standard. He advocated 

 a plan of examination which is partly car- 

 ried out at the School of Science, South Ken- 

 sington. That was, to study and be exam- 

 ined on each subject separately, and by the 

 same persons who had acted as teachers. 



The Fntare of Physiological Experiment. 



— Professor Tyndall founds a new argument 

 in favor of the practice of experimental 

 physiology in the peculiar properties of in- 

 fectious diseases, and their probable germ 

 origin. One of the most extraordinary and 

 unaccountable experiences in medicine has 

 been the immunity secured by a single at- 

 tack of a communicable disease against fu- 

 ture attacks of the same malady. Small-pox, 

 typhoid, and scarlatina, have been found, 

 for example, as a general rule, to occur only 

 once in the lifetime of the individual, the suc- 

 cessful passage through the disorder seem- 

 ing to render the body invulnerable against 

 future attacks. Professor Tyndall had some 

 time ago suggested to a friend that the 

 phenomenon could be explained under the 

 germ theory by supposing the soil, or the 

 system, to be exhausted by the first para- 

 sitic crop, of some ingredient necessary to 

 the growth and propagation of the parasite. 

 Some important essays on the subject have 

 been recently published in the " Revue Sci- 

 entifique " by M. Bouley, who draws atten- 

 tion to the results obtained by M. Raulin in 

 the cultivation of the microscopic plant As- 

 pergillus niger. The omission of potash 



from M. Eaulin's liquid suffices to make the 

 produce fall to one twenty-fifth of the amount 

 collected when potash is present. The ad- 

 dition of an infinitesimal amount of a sub- 

 stance inimical to the life of a plant is at^ 

 tended with still more striking results. For 

 example, one part in 1,600,000 of nitrate of 

 silver added to the liquid entirely stops the 

 growth of the plant. Now, supposing the as- 

 pergillus to be a human parasite — a living 

 contagium — capable of self-multiplication in 

 the human blood, and of so altering the con- 

 stitution of that liquid as to produce death ; 

 then, the introduction into the blood of a 

 man weighing sixty kilogrammes, of five mil- 

 ligrammes of nitrate of silver would insure, 

 if not the total effacement of this conta- 

 gium, at all events the neutralization of its 

 power to destroy life. An index-finger here 

 points out to us the direction which physio- 

 logical experiment is likely to take in the 

 future. In anticipation of the assault of 

 infectious oi'ganisms, the experimenter will 

 try to introduce into the body substances 

 which, small in amount, shall so affect the 

 blood and tissues as to render them unfit for 

 the development of the contagium. And, 

 subsequent to the assault of the parasite, he 

 will seek to introduce substances which shall 

 effectually stop its multiplication. Dr. Polli, 

 of Milan, has already obtained results that 

 promise well with alkaline sulphides in cer- 

 tain fevers and small-pox, and Crudelli ob- 

 tained similar results with arsenic against 

 the malaria of the Roman Campagna. To 

 enable us to administer these remedies safe- 

 ly and with some assurances of success, ex- 

 periments must be made of their effects, on 

 different groups of individuals, and these 

 individuals must be animals susceptible to 

 the infection and to the counteracting appli- 

 cation. " I appeal," says Professor Tyndall, 

 " not to the partisans of either side, but to 

 the common sense of England, whether, in 

 the interests of humanity, the proposed ex- 

 periment is not a legitimate one." 



Effect of School-Work on the Brain.— 



A question was recently asked Mr. Mun- 

 della, m the British House of Commons, as 

 to the effect of the English educational sys- 

 tem on the health of children and teachers. 

 He replied in substance, availing himself of 

 the reports of the Lunacy Commissioners, 



