POST-MORTEM INTRAUTERINE CHANGES. 297 



However, since Panum found deformations especially common in the cephalic 

 extremity, and further stated that many of his so-called "monstruositates totales 

 cylindricse" were mummy-like, with features effaced, it seems more likely that he 

 was dealing with maceration forms the death of which was due to the chilling. 

 Just why some chick embryos, the heart-beat of which has been temporarily sus- 

 pended by chilling, die quite promptly, and others only late in development, 

 near the end of the normal incubation period, I do not know, but personal observa- 

 tions leave no doubt regarding this matter, and variation in vitality is all that 

 I can suggest as an explanation at present. 



It is only just to state that Panum considered the possibility that the anoma- 

 lous forms were secondary in origin, and concluded that some were germinal in 

 origin. His (1891), too, at first regarded certain abnormal forms of human embryos, 

 such as the nodular, cylindrical, and flexed (geknickte), as germinal, but later 

 inclined to the belief that they nevertheless arose from changes occurring after 

 the death of the embryo, saying: 



"Seitdem ich mir aber Rechenschaft gegeben habe von den histologischeu Ver- 

 anderungen welche eine Folge des Absterbens sind, von der Quellung des Gehirns und 

 den Veranderungen der urspriinglichen Gewebe durch eine Zellenbrut, bin ich weit 

 mehr geneigt, die abortiven Formen von Embryonen als secundar enstanden anzusehen. 

 So werden speciell auch die so auffalligen Cylinderformen verstandlich, sowie man sich 

 davon Rechenschaft giebt, dass von dem friiheren Embryo neben einem auffalligen Skelett 

 fast nur noch die Haut ubrig geblieben ist. Als ausdehnbarer Sack kann sich dieselbe 

 mit fremdem Material, mit Wanderzellen und zum Theil mit Fliissigkeit ausfiillen und 

 nun giebt sie die alten Korperformen nur noch in den allergrobsten Ziigen wieder." 



In spite of these words, His insisted that poorly preserved normal forms never 

 show changes seen in so-called abortive forms, and emphasized that, although the 

 cells in abortuses may not all be dead, we nevertheless can not speak of these 

 abortive forms as living. 



The mere fact that post-mortem changes may produce misleading modifica- 

 tions in form makes the identification of post-mortem deformations extremely 

 important. If all conceptuses were aborted immediately after their death, the 

 problem would be a far simpler one, for such an event would at once dispose of 

 such difficult questions as, not only those of survival, but also of the independent 

 growth of one or more members of the cyema, or of the whole of the vesicles, after 

 the death of the cyema. That outward apparent stunting is a fairly common 

 occurrence in young embryos is fully attested by the many specimens in the 

 Carnegie Collection which illustrate this phenomenon, but I have not been able 

 to find convincing proof indicating that it is also physiological. In the case of 

 older fetuses with apparent brachydactyly, osseous development seems to have 

 been normal and the modifications attributable to changes in the soft parts. Hence 

 I am prompted to conclude that, although growth may be retarded in consequence 

 of circulatory disturbances, it continues wholly normally, unless influenced by other 

 things, until the heart stops. 



It also may be difficult to tell whether a given condition arose before or after 

 death of the embryo, merely because of the presence of maceration changes, even 



