September 15, 1916] 



SCIENCE 



373 



from too great arterial blood pressure. 

 Later, Ludwig and his pupils established 

 more definitely the seat of the vaso-motor 

 centers, and showed that the veins as well 

 as the arteries of the portal system are 

 under the control of nerves. Mall, now at 

 Johns Hopkins, who worked with Ludwig 

 in 1885, established this last fact. 



It was Ludwig who started Mosso on the 

 development of the plethysmographic 

 method, by which the volume changes of 

 organs under the influence of the altera- 

 tions of the blood supply have been studied 

 by many investigators,. e. g., Edmunds has 

 found it of great value in work which he 

 has been doing in the past years. 



Ludwig 's cleverness in inventing instru- 

 ments required for his investigations is to 

 be seen in the Stromuhr, by the use of 

 which he was able to succeed where others 

 had failed, and to measure the rate of the 

 flow of the blood stream. By means of this 

 he measured the rate of the output from 

 the heart under varying conditions, and the 

 amount of blood flowing through special 

 organs when at rest and in action. 



He was always deeply interested in re- 

 flex processes, and many experiments were 

 carried on in his laboratory on the paths 

 taken by nervous impulses along the white 

 matter of the cord, summation processes, 

 and the effect of local excitations and 

 poisons. In addition, he caused many re- 

 searches to be made on the special senses, 

 sight, hearing and taste. 



Investigations of a chemical nature were 

 also made at his instigation, and von Frey 

 has pointed out the difficulties which he 

 must have encountered in directing such 

 work, lying as it did outside of the fields 

 with which he was most conversant. From 

 the time that Ludwig and Alexander 

 Schmidt found that easily oxidizable sub- 

 stances pass from the tissues into the blood, 

 many such intermediate products were dis- 



covered in the chemical side of the labora- 

 tory, and their distribution through the 

 body followed. Cloetta discovered the 

 presence of inosit, uric acid, etc., in the 

 animalbody ; calcium andphosphoric acidin 

 the blood were measured; the lessening of 

 glycogen in the "uberlebender" liver was 

 noted; and the origin of jaundice studied. 

 The method by which fats are absorbed, the 

 streaming of fat in the lymphatics, the 

 constitution and the fate of the fats enter- 

 ing the blood, all received attention. The 

 digestion and absorption of proteins and 

 sugars, and the changes which they undergo 

 after entering the body were investigated, 

 the structure of albuminous bodies being 

 made the subject of special study by 

 Drechsel. 



An interesting discovery was made while 

 the method of absorption of the digestion 

 products of protein was being studied, 

 namely, that albumoses if introduced di- 

 rectly into the blood act as poisons and 

 deprive the blood of its power to coagulate. 

 This observation gave a new impulse to the 

 study of coagulation, and of the formed 

 elements of the blood. 



I am conscious of the incompleteness of 

 this hasty summary of the work of Ludwig 

 and his pupils. 



Ludwig, himself, was deeply impressed 

 with what had been accomplished, and the 

 wide field of knowledge which had been 

 opened up to man. I remember that he 

 said the last time that I saw him, "What 

 a pity that one must die just as it begins 

 to be so interesting." 



I can not close this paper without a few 

 words concerning Ludwig 's private life. 

 He was no lover of forms and ceremonies, 

 and counted of little worth the honors con- 

 ferred by the so-called "great." I chanced 

 to be present when a student called in 

 dress coat and white gloves at the formal 

 noon hour, as was the custom, to ask his 



