PREFACE. 



ception in any and all stages of development, even up to birth, has prompted me 

 to resort to additional terms. It certainly would seem best to restrict the term 

 ovum to its comparative embryological significance and thus avoid confusion. 

 But this restriction leaves us without a word to designate the whole product of 

 conception. For this the word conceptus seemed available. At present the word 

 embryo is frequently used loosely to designate conceptuses of any age. It is used 

 still more frequently to designate merely the body of the future individual during 

 the early stages of its development, in contradistinction to the word fetus, which 

 usually is restricted to the later months. Hence we have need for still another 

 term to be used in common for the embryonic disk, the embryo, or the fetus. 

 Dr. Schultz has kindly suggested kyema, which Professor Foster suggests is prefer- 

 ably spelled cyema, adding that it is excellent Greek and was used in the proposed 

 sense by Plato himself. It also has the advantage of being available for compara- 

 tive embryology and of being easily adapted to meet such needs as are represented 

 by the terms cyemetric and cyemology. Change may not imply improvement or 

 progress, but the absence of it certainly never does. I realize fully that the use 

 of unnecessary terms is to be avoided, but this is equally true of awkward circum- 

 locution and misunderstanding. When one writes or says at present that no 

 embryonic remnants were seen, it is impossible to know what is meant. Although 

 the word embryo could by common consent be used in the proposed sense of cyema, 

 long usage probably would make such an attempt futile for this reason alone. The 

 use of this term and of others, presently to be suggested, does not change old mean- 

 ings or old usage. It abrogates nothing save confusion. 



Although the word abortion is available to designate the individual or the 

 material aborted, it has not been the custom to use it in this inclusive sense. The 

 word abortion, as now used, is usually restricted to the act itself. To use it in a 

 double sense would lead to some confusion. Since blood-clot, pus, decidua, and 

 mucosa usually are not only included with but frequently also surround the entire 

 conceptus, I have used the word abortus to designate all the material expelled 

 during an abortion. Only in this way can one avoid the use of such words as ovum, 

 mole, chorion, and such expressions as the entire mass, embryonic mass, abortion mass, 

 or (quite inaccurately) the chorionic vesicle, even when the latter is surrounded by a 

 certain amount of decidua and blood-clot. 



Since the term fetus compressus, as customarily used, refers to a twin fetus 

 which died and was later subjected to pressure from the surviving, growing fetus 

 during an extended period of time while it was undergoing mummification, the 

 use of this term in Chapters III and IV requires definition. Practically all the 

 specimens so designated in this survey are single, not twin. Besides, they have 

 but rarely been subjected to pressure, and not a single specimen is dehydrated 

 to the extent of being papyraceous. Rarely, when fetuses so termed have been 

 subjected to pressure, this was the pressure of the contracted uterus subsequent to 

 the absorption of the amniotic fluid. In many instances, however, these speci- 

 mens were contained in a quantity of amniotic fluid sufficient to be protected from 

 direct pressure of the uterus transmitted through the fetal membranes. More- 



