Franklin V. Mall 145 



general anatomy, associated with the name of Bichat, the cell doctrine 

 with that of Schwann, and histogenesis with that of His. Compare 

 the great text-books of anatomy of 1790 with those of ISIO, those of 1830 

 with those of 1850 and those of 1880 with those of 1900 and the rea- 

 sons for this statement will be apparent. 



At the time His began his embryological studies the plan of the de- 

 velopment of the vertebrate bod}', as enunciated by Von Baer with 

 Eemak's classification of tissues, had been accepted generally. But the 

 work of Eemak was incomplete and in some respects unsatisfactory as, 

 for instance, his conclusion regarding the development of the nervous 

 system, the central portion of which he believed arose from the ectoderm 

 and the peripheral portion from the mesoderm. This and other defects 

 were corrected by His who made a new classification of tissues and germ 

 la3'ers which differs more from Eemak's classification than this in turn 

 did from. Yon Baer's. 



In the " Program " His also showed that there is an embryological 

 foundation for Bichat's classification of membranes since they are related 

 directly to the germ layers. Further, he extended the conception of the 

 serous spaces to include the vascular system. All of the serous spaces 

 arise in the mesoderm, and His showed that they are lined with a special 

 kind of cell, designated from the time of his paper on, as endothelial. 



After this, his greatest work was histogenetic — witness for instance his 

 studies upon the nervous system and upon the development of the blood- 

 vessels. Contribution after contribution was published upon histogene- 

 sis. During the last years of his life he often complained to me that his 

 time was short and that it was necessary for him to make haste in order 

 to round up his work. 



Thus His continued to l)e active until he was over seventy years old; 

 his final papers, " although fragmentary," are of the highest quality. 

 In his great paper upon the angioblast he gave his latest classification of 

 tissues from an embryological standpoint^ and stated in conclusion that 

 the riddle which had interested him so much still remained unsolved. 

 Similarly, in his last monograph upon the nervous system, he wrote: 

 " The notes are not to be considered as a report of a finished research, 

 but thev only indicate the line of work which must be followed by united 

 effort* in order that a better understanding of the structure of the brain 

 may be gained." He saw more and more clearly that many hands are 

 required to survey these great fields and during the last twenty years of 

 his life, thought much about the organization of research. He lived to 

 see his efforts in this direction crowned by the establishment of a com- 



