CYLINDRICAL CYEMATA. 81 



the fragment of the embryo and the torn chorionic vesicle were being extruded 

 from the tube, for they lay some distance distal to the site of implantation. No 

 remnant of a cyema, definitely recognizable as such, remained in No. 342, but a 

 small conical mound of cells, located at the distal extremity of the cord, neverthe- 

 less may have been a remnant of it. The few sections of a portion of the cyema 

 found in No. 874 suggest that the development of this specimen apparently had 

 not been changed greatly. 



GBOUP 5. CYLINDRICAL CYEMATA. 



A. UTERINE. 



The cylindrical specimens forming this group comprised 7.5 per cent of the 

 first 1,200 accessions or 18.9 per cent of the pathologic. Hence the frequency of 

 the cylindrical cyemata is far greater than that of the nodular, although it must 

 be remembered that the group of cylindrical contains some specimens which are 

 not embryos at all, but merely remnants of the cord. 



As already stated, this group is not separated from the preceding or succeeding 

 group by any definite division. Transition forms could easily be found. However, 

 since the limb-buds begin to appear at a length from 4 to 5 mm., it is evident that 

 the specimens in this group also must be small, for as soon as limb-buds have 

 fairly developed an age is reached in which stunting becomes evident and the 

 specimen then falls into the next group. The inference is not that stunting becomes 

 evident in the extremities only, but that it is quite easy to recognize it here with 

 the unaided eye. Not all the specimens of this group are less than 4 or 5 mm. 

 in length, however; for even when they are exceedingly atrophic or when miniature 

 limb-buds are present, it is sometimes impossible to distinguish the cephalic from 

 the caudal extremity in the presence of an atrophic cephalic region. Consequently, 

 some specimens rightfully belonging in the next group remain among the cylin- 

 drical; and since the classification is determined very largely by gross appearances, 

 portions of the umbilical cord also are frequently classed in this group. On many 

 of these not a remnant of the cyema can be found, even upon microscopic examina- 

 tion. But since the absence of remnants of the body of the cyema may be due 

 solely to mechanical interference, it follows that some specimens of wholly normal 

 conceptuses become included in this group. 



The largest cyema is No. 710, which has a length of 13 mm. The next is 

 No. 288a, which is 11 mm. long. Both of these fetuses are macerated and the 

 organs are greatly dissociated. Had they been better preserved, stunting could 

 have been recognized and they would undoubtedly have been classed in the next 

 group. These considerations, and the further fact that extremities were present, 

 seem to suggest that the causes which contribute to the death of these cyemata 

 apparently do not wholly prevent the development of the extremities or retard 

 their growth appreciably beyond the retardation felt in other parts of the body. 

 This conclusion does not imply, however, that the changes produced in the ex- 

 ternal form and structure of cylindrical cyemata may not have been pronounced. 

 A reference to figures 22 to 28 will show that this is the case. To what extent 



