NOVEMBEB 8, 1907] 



SCIENCE 



633 



after thirteen years it must be said that the 

 hopes then awakened have been more than 

 realized. Thousands of lives have been saved 

 and the once dreaded scourge of diphtheria 

 has been robbed of its horrors. However, the 

 dream that an antitoxin for each and every 

 one of the infectious diseases would be secured 

 within a few years has not developed into a 

 reality and is not likely to do so. Indeed, 

 it is possible that the attempt to work out an 

 antitoxin for typhoid fever has delayed the 

 discovery of the true method of treating that 

 disease. 



Professor Barker discourses on " the 

 neurons," the theory of which has aroused 

 much diseiission and some bitterness of expres- 

 sion among histologists and it is all about the 

 exact relation between the nerve cells and the 

 nerve fibers. However, this is by no means a 

 matter of trifling importance, because upon it 

 rests problems not only of structure, but of 

 function as well. The theory, founded largely 

 upon the work of His, Forel and Cajal, was 

 evolved by the genius of Waldeyer and it sup- 

 poses that there is no nerve fiber independent 

 of nerve cell and that the cell with all its 

 prolongations is a unit or a neuron; that 

 these units are not united to one another 

 anatomically, but act together physiologically 

 by contact; that the entire nervous system 

 consists of superimposed neurons ; that the 

 neurons are so arranged that an impulse can 

 pass only in one direction and starting in 

 the dendrites it is carried to the cell body 

 and thence along the axis cylinder to the 

 dendrites of another neuron; that every part 

 of the neuron is dependent for its nutrition 

 on the nucleus of the cell body, and that 

 when a nerve fiber is injured or severed the 

 regeneration of the axis cylinder is accom- 

 plished by an outgrowth from the central end 

 and in no other way. This theory has met 

 with wide acceptance, but also with some 

 strong opposition. The most vigorous op- 

 ponents being Apathy, Bethe and Nissl; and 

 Professor Barker, while supporting the theory 

 is generous in his estimate of the value of the 

 work done by these men. The lecture is most 

 instructive and brings the whole subject up to 



date (January, 1906). The important work, 

 illuminating this subject, done by Harrison is 

 mentioned and has been more fully developed 

 since. 



Professor Lee discusses the old, but always 

 interesting, subject of " fatigue." Why do we 

 tire, is it in the nerve or the muscle, and 

 what are the fatigue-producing substances? 

 The nerve-muscle machine is a great inven- 

 tion, the first used by man, and still there are 

 many things about it and its action that we 

 do not understand. The scientific study of 

 fatigue has been carried out largely by Mosso 

 and his students and the ergograph in its 

 improved form gives accurate results. The 

 weight of evidence at present is that the 

 nerve is not fatigued and that the tired sensa- 

 tion is due to peripheral exhaustion. How- 

 ever, the question in all its details can hardly 

 be considered as finally settled. Hodge and 

 others have demonstrated microscopical 

 changes in certain nerve cells after muscular 

 exertion and the experiments of Sherrington 

 seem to show that in fatigue there must be 

 something at fault in the nervous connections. 

 He takes a spinal center which has several 

 afferent tracts and but one efferent to a given 

 muscle, and he finds that when he has ex- 

 hausted the muscle by stimulation through 

 one afferent nerve, it acts with renewed vigor 

 when the stimulation is sent through another. 

 The muscle, the motor nerve and the center 

 are the same and renewed vigor is secured by 

 sending the stimulation through another 

 afferent. Sherrington tliinks that the trouble 

 lies at the point of contact between the affer- 

 ent and efferent neurons. The fatiguing 

 metabolism products are believed to be potas- 

 sium acid phosphate, sarcolactic acid and 

 carbonic acid. The statement of Weichardt 

 that he had not only found a toxin that is 

 responsible for fatigue, but had produced an 

 antitoxin with which weary people might be 

 treated, seems to have met with but little ap- 

 preciation. 



Professor Mandel points out the " recent 

 advances in our knowledge of the formation 

 of uric acid." It was formerly believed that 

 uric acid was a product of deficient oxidation 



