PREFACE. 7 



As our knowledge of the normal becomes more complete, we find that more 

 and more young embryos which formerly were regarded as normal are not really so. 

 The literature of human embryology contains many such instances, and it was 

 impossible, and it remains impossible even at the present time, to determine in all 

 cases whether we are dealing with a normal or an abnormal specimen, even after 

 it has been mounted in serial sections. Hence it happens that abnormal human 

 embryos and fetuses still are represented as normal in contemporary embryologies. 

 It has often seemed to me that there is one source of material which could bring 

 much help in this connection. If the many tragedies with which our coroners 

 come in contact could always be utilized scientifically, as they rarely have been 

 in the past, much desired information would soon be in our possession. It seems 

 that a very promising opportunity for progress lies here. In an intelligent com- 

 munity public opinion will, I believe, gladly support any one in such utilization of 

 these chance cases as soon as a broadly humanitarian, even if not a keenly scien- 

 tific, attitude can be cultivated on the part of our coroners. 



What can be accomplished through cooperation between public officials and 

 laboratory workers was illustrated by the fine assistance given Professor Mall 

 and the Department of Embryology of the Carnegie Institution of Washington by 

 the department of health of the city of Baltimore. Indeed, one can not recall this 

 service without feeling the deepest regret that similar cooperation, especially with 

 coroners, has not yet been realized in more American municipalities. Such co- 

 operation, supplemented by that of the practitioner, especially in obstetrics and 

 gynecology, can accomplish much in the course of years. But cooperation between 

 laboratory workers also is necessary. Even the chemist, not only the pathologist, 

 is indispensable. Without him the anatomist often is helpless. Here, for example, 

 is an unopened, fairly normal looking abortus composed of a clean conceptus. 

 The periamniotic fluid, to all appearances, is absolutely normal. The interior 

 of the chorionic vesicle also appears normal. The amniotic vesicle, although 

 much smaller than one would expect, is normal in all other respects and distended 

 moderately with perfectly clear and absolutely normal-looking fluid; yet such a 

 conceptus may contain not even a trace of an embryo, even if the yolk-sac still 

 looks normal. Such specimens are rare, but they occur, and one of the things 

 wholly inexplicable to the anatomist is not so much the absence of the embryo as 

 the fact that its disintegration has not resulted in the least turbidity of or deposit 

 in the amniotic fluid or the dissolution of the amnion. Even a microscopic examina- 

 tion of the fluid may fail to reveal any cellular content. The anatomist desires 

 to know not merely in what respects the composition of the intra-amniotic and 

 periamniotic fluids has been changed, but what the enzymes are that have caused 

 the complete lysis of the embryo, from what these arise, and how they become 

 active. These and many other questions the chemist only can answer. For this 

 answer fresh material is indispensable, but this the neighboring practitioners or a 

 closely associated clinic can supply. I am aware of the fact that chemists and 

 physiologists have not neglected these questions, but at present our knowledge 



