POST-MORTEM INTRAUTERINE CHANGES. 291 



One might expect that maceration, even under sterile conditions, especially 

 in case of young specimens, would result in general distention, but this does not 

 always seem to be the case. Edematous areas do, indeed, frequently form locally, 

 as previously illustrated and as generally observed; but swelling due to imbibition, 

 such as occurs when fresh young specimens are placed in formaldehyde, was 

 observed only in a minor degree, as illustrated by No. 2146, shown in figure 187. 

 Sometimes this swelling is local, as represented by the cephalic region of No. 

 1750. A subsequent reduction in size is much more common and may be due to 

 absorption of salts from the amniotic fluid, with resultant concentration of it and 

 of extraction of tissue fluid from the cyema itself. In very young specimens, such 

 as No. 786 (fig. 189), an embryo 4 mm. long, the first noticeable shrinkage change 

 in form seems to occur in the cephalic extremity, the frontal prominence of 

 which recedes and the outline of the vertex of which becomes more and more 

 rounded and also is reduced in size. 



In consequence of these changes, the cephalic extremity becomes relatively 

 too small, as is well illustrated by comparing this specimen with No. 1380, shown 

 in figure 190, a cyema of the same development but 5.5 mm. long and in an excel- 

 lent condition of preservation. This reduction in size of the cephalic region would, 

 to be sure, result in a reduction in length were the measurement taken from tip 

 to tip, and were it not for the fact that during this process the cephalic extremity, 

 if indeed not the entire embryo, usually unbends and in becoming straighter com- 

 pensates for, or even more than compensates for, the loss in length due to reduc- 

 tion in size of the cephalic extremity. This does not always occur, however, as Nos. 

 1299 and 2216 so well illustrate (see figs. 191 and 192). These changes make the 

 trunk look disproportionately large and the features somewhat stunted. Previous 

 to these changes, or coincident with them, the tissues lose their elasticity and also 

 become softer, and the surface of the specimen becomes duller, more opaque, and 

 finally more yellowish. Other changes noticeable in the specimen just referred to 

 are the loss in detail of the surface relief, evident particularly in the branchial 

 region, and in the effacement of the myotomes. In other instances, such as No. 

 2035 (a portion of a tubal specimen), a marked change is very evident in the caudal 

 extremity, which has become shorter, blunter, and straighter, although upon close 

 inspection other changes also are noticeable. Because of these things the actual 

 soon may become less than the original length and only roughly indicate the true 

 age of the cyema. 



The change in the cephalic extremity, the decrease in the natural curve 

 which accompanies erection of the specimen, and the loss in detail just spoken of 

 are illustrated still better by No. 187a, which is a somewhat older embryo, 7 mm. 

 in length. Young embryos which illustrate the early changes in form are Nos. 

 208 and 1296, shown in figures 193 and 194 embryos which are respectively 7 

 and 4 mm. long in their present state. 



A somewhat similar, though slighter, effect of maceration upon relatively 

 young specimens is illustrated by Nos. 1697 and 1477, shown in figures 195 and 

 196, cyemata 15 and 18.5 mm. long respectively. In the first of these two speci- 



