246 Genetic Interprt'tations in the Doinain of Anatomy 



It is sonictinies said, and perliaps inoro often thouglit, tliat anatomy 

 is a completed science. This assertion is based upon the thoroughness 

 and exhaustive character of the descriptions to be found in our text- 

 books of the anatomical conditions in the human adult; yet even as 

 regards the organization of the adult we have still much to learn, espe- 

 cially concerning the microscopic structure with which we are still very 

 imperfectly acquainted. 



But anatomy is not alone a descriptive science. It is also comparative 

 and genetic. In both these directions its development is very far from 

 complete, and a vast amount of original research must still be completed 

 before comparative anatomy and embryology shall have approached any- 

 where near even the present perfection of descriptive human anatomy. 



To embryological research must be attributed a large part of the 

 extraordinary progress Avliich anatomy lias made during the last twenty- 

 five years. By embryology we have gained a far deeper understanding 

 of all anatomical forms, we have acquired new interpretations for path- 

 ological facts, and we have secured for the first time some clear insight 

 into the essential structure of the brain. I need not do more than 

 allude to these achievements, since they are familiar to us all, and have 

 most profoundly affected our anatomical conceptions. Our point of view 

 has changed, and we interpret the anatomy of the adult in terms of the 

 genesis of the organs and tissues during their embryonic development. 



Perhaps no man has contributed so much towards this result as the 

 great Leipzig anatomist, Wilhelm His, whose death this year we have 

 to lament. He was a great master. He had full command over the prob- 

 lems of anatomy and contributed in the richest measure to their solution. 

 His influence in America has been especially strong and widespread, and 

 has certainly had much to do in bringing about the progress of anatomy 

 in this country, which we are seeking to maintain, and if possible, in- 

 crease. In what I have to say to you on this occasion, you will perceive 



Phrenic area, the area on the superior or cephalad surface of the liver, by 

 •which the liver is attached permanently to the diaphragm. It includes 

 the whole of the territory of the coronary and triangular " ligaments," so- 

 called in current text-books. 



Sinusoid, an irregular blood space, produced by the subdivision of a larger 

 blood-vessel by the ingrowth of the parenchyma of an adjacent organ. 



Structural unit, the territory of an organ supplied by a single terminal 

 branch of an afferent vessel (artery or vein) ; the volume of such a unit 

 is often only 10-20 cubic millimeters. 



Trophoderm, the special layer of cells formed on the exterior of the 

 young mammalian blastocyst, and serving to secure the implantation of the 

 ovum in the uterus. 



