634 



SCIENCE 



[N. S. Vol. XXVI. No. 671 



and its presence in unusual amount in the 

 urine led to the administration of oxidizing 

 agents, such as nitrohydrochlorio acid. Hor- 

 baezewski was the first to give us a start in 

 the right direction in the study of uric acid 

 metabolism, and we now know that, in a gen- 

 eral way at least, the amount of uric acid 

 formed is a measure of the metabolism of 

 nucleoproteids, and since these are found in 

 our daily food we have two sources of uric 

 acid: the exogenous that comes from the 

 nucleoproteids of the food, and the endogenous 

 that result from, the metabolism of the nucleo- 

 proteids of the body itself. Quite naturally 

 the daily output from the first source is quite 

 variable, depending upon the kind and amount 

 of food, while that from the second source is 

 fairly constant in the individual, but quite 

 variable as between individuals. However, all 

 the uric acid formed in the body is not elimi- 

 nated as such and there is some doubt as to 

 the form in which the lost part is eliminated. 

 It may possibly be converted into urea, allan- 

 toin, glycocoll or oxalic acid, or into two or 

 more of these. In this connection the recent 

 suggestion of the etiological significance of 

 glycocoll in gout is interesting. 



Professor Morgan is not ready to satis- 

 factorily explain why " the power to regenerate 

 lost members " is so feeble in man and other 

 high vertebrates compared with the ready 

 regeneration observed in some of the lower 

 animals; however, he thinks that it is due to 

 the fact that the different tissues regenerate 

 at different rates and consequently there is 

 lack of cooperation and harmony in develop- 

 ment. The skin regenerates ; the muscle does 

 so, though less well; nerves and blood- 

 vessels regenerate, and the bones have a not 

 inconsiderable power to mend. Hence, the 

 failure to develop a new limb does not appear 

 to be due to the failure of the individual 

 elements to regenerate, but to their failure to 

 regenerate concurrently. 



Professor Minot offers an interesting scien- 

 tific explanation of " the nature and cause of 

 old age." He thinks that senescence is due to 

 a relative increase of the protoplasmic to that 

 of the nuclear" content of the cell. " Growing 



old, in other words, consists primarily in aa 

 increase in the proportion of protoplasm. 

 We thus have a cytological mark by which old 

 age can be distinguished, and we are able to 

 connect senescence with visible changes in 

 cells : we are able to say there is a histological 

 basis or cause of old age." He shows that the 

 animal grows old most rapidly during intrau- 

 terine life and that after birth the rate of 

 growing old decreases. However, what is 

 ordinarily denominated as old age is, from the 

 intellectual side at least, the reaching of a 

 point where the accumulated losses result in 

 comparative mental fixity. Changes in the 

 nervous system diminish its adaptability and 

 we are not able without ever-increasing dif- 

 ficulty to turn to new forms of mental ac- 

 tivity. We may continue to do well the kind 

 of thing which we have learned to do, but if 

 we try to overstep the limits of our acquired 

 expertness we find that we are held up by a 

 sense of permanent mental fatigue. 



Professor Webster discusses quite exhaust- 

 ively " modern views regarding placentation " 

 and the text is accompanied by explanatory 

 figures. 



Professor Smith discourses in a broad, sci- 

 entific way upon " the parasitism of the 

 tubercle bacillus and its bearing on infectioa 

 and immunity." The thesis held is that the 

 tendency of such a chronic disease as tuber- 

 culosis is towards a balanced parasitism with 

 reduced mortality but probably with increased 

 morbidity. The efl^ect of immunization of 

 man, if it ever can be attained, on the destiny 

 of the tubercle bacillus is an open question. 

 Trying to stamp out tuberculosis by increas- 

 ing man's resistance should be secondary to 

 efl^orts to destroy the bacillus. The former is 

 a compromise and a recognition that the 

 bacillus is here to stay, and if it be permitted 

 to continue among us, as we increase our re- 

 sistance, it will probably grow in its virulence. 

 Increased resistance may save the individual, 

 but to save the race we should destroy all 

 tubercle bacilli, and knowing how they find 

 access to the human body and how they leave 

 it, this does not seem an impossible task. Cer- 



