March 15, 1918] 



SCIENCE 



255 



Dr. Mall in the same journal, in which he 

 states frankly, "Sie haben gegen mich 

 Il«eht." This letter cemented a lifelong 

 friendship, as can be readily seen from cor- 

 respondence accompanying Dr. Mall's 

 article on "An Estimate of the Work of 

 His." 



During the winter of 1885, His suggested 

 that Dr. Mall work under the great phj'siol- 

 ogist, Ludwig. As Ludwig's laboratory 

 was always full, the opportunity was slow 

 in coming ; indeed, as Dr. Mall wrote home, 

 he was leaving Leipzig with no hope ; his 

 trunk was even on the way to the station 

 when the letter came that the opportunity 

 he so much desired was his. So great was 

 the influence of Ludwig over his mind, 

 character and future work, that it is im- 

 possible to overestimate it. He himself 

 summed it up in these words: "To that 

 master I owe much — all." Ludwig as- 

 signed to him the study of the villus of the 

 intestine. His first impression of his new 

 problem, as gathered from one of his letters 

 home, was that here was a subject which 

 had occupied the minds of the greatest 

 anatomists of the past century. Re- 

 peatedly throughout Dr. Mall's writings 

 there is to be found that expression of re- 

 gard for the work of great minds. Widely 

 read in his own subject, it was of the works 

 which have lived that he made a profound 

 study. 



In Ludwig's laboratory Dr. Mall learned 

 the methods of injecting blood-vessels and 

 lymphatics, and his studies on the vascular 

 sj-stem of the intestine and stomach are fa- 

 miliar to every student of medicine. 

 Under the influence of Ludwig, his work 

 was characterized by a very strong phj-sio- 

 logical bent. Indeed it may be said that 

 his work was physiology in the hands of 

 one with an intense interest in structure. 



In some of the foreign universities it was 

 the custom for a new incumbent of a chair 



to deliver an address giving, as it were, a 

 "prophecy" or a "program" of his future 

 work. Such a program was the famous ad- 

 dress of His on accepting a chair in the 

 Swiss University of Basel. In some such 

 way the article of Dr. Mall on the stomach, 

 published in the first volume of the Johns 

 Hopkins Hospital Report, gives his program 

 of the way he proposed to study anatomy. 

 This paper lays a foundation for what may 

 be called physiological anatomy. He stud- 

 ied the stomach from every aspect and 

 with a wide range of methods. Here is the 

 beginning of his brilliant work on the fibers 

 of the connective tissues; here the studies 

 on the normal contraction-wave of smooth 

 muscle and the experiments on the reversal 

 of those waves. In his paper on the stom- 

 ach is this brief note : 



Recently I have found that irritation of the 

 splanchnic nerve causes contraction of the mesen- 

 teric vein. 



He probably first made this observation 

 in Ludwig's laboratory and subsequently 

 proved that the portal vein is supplied with 

 vasomotor nerves, a valuable discovery in 

 physiology. 



The most important idea of this early 

 work from the standpoint of anatomy is 

 that of structural units, which Dr. Mall 

 conceived from the study of the villus. 

 The theory reaches its best expression in 

 Dr. Mall's articles on the liver and spleen. 

 It is that organs are made of ultimate his- 

 tological units, represented in the vascular 

 system by the capillary bed which inter- 

 venes between a terminal artery and its 

 corresponding vein. Thus the size of the 

 unit is determined by the length of the 

 capillary. These units are grouped to- 

 gether into lobules. They are not only of 

 great structural significance, since an organ 

 is to be considered as a multiplication of 

 them, but they are also of significance to 

 physiology since such units are equal in 



