ARREST OF DEVELOPMENT. 59 



The tissues are all abnormal \ great hypertrophy of the connec- 

 tive tissue is frequent. The neural canal is seldom normal ; it is 

 more frequently absent or open, or its cavity communicates with 

 large cysts. Parts of the skeleton may be tolerably well formed ; 

 sometimes there are four imperfect limbs, or there may be one 

 or two more or less well-formed limbs only. The alimentary 

 canal is always in a very imperfect condition from obvious arrest. 

 They appear to be always twins to perfect foetuses. Nos. 135 

 and 137, examples of encysted foetuses, exhibit precisely similar 

 conditions. 



238. A Human male foetus without any head or heart. The 



whole body is very oedematous, and has been much dis- 

 torted by the manner in which it was originally suspended. 

 Three extremities are better formed than the remainder of 

 the body; the left anterior, extremity is, however, a mere 

 shapeless mass. The spine has been exposed behind, and 

 its laminae removed on one side to show the cord. It has 

 a single curve with its convexity backwards, and consists 

 almost entirely of cartilage, but is otherwise normal. 



239. The right half of an acephalous acardiac foetus, which has 



been divided longitudinally in the median line. The ver- 

 tebral column is truncated at either extremity, and con- 

 sists of twenty-two segments, with a large spheroidal bony 

 nucleus in each segment, except the first three. 

 The neural canal is closed in by laminae ; it contains a cord, and 

 its upper extremity is filled up and closed by a fibrous mass contain- 

 ing a small cyst. A proboscis ending in an ovate knob terminates 

 the axis in front externally. The thoracic and abdominal cavities are 

 not separated from each other. The upper and back part of the 

 body-cavity is filled with a dense mass of connective tissue closely 

 united to the spine, and probably representing the lungs, with an 

 empty cavity in front bounded anteriorly by a small sternum, pro- 

 bably pericardial. The lower part contains one great median kid- 

 ney, a pair of ureters, and a urinary bladder. The external sexual 

 organs are too imperfect to denote the sex. There are apparently 

 no internal generative organs. There is no liver. The intestine com- 

 mences blindly in a sac in the cord and terminates in a rectum, which 

 is impervious. The integument is much hypcrtrophied. The arm is 

 very imperfect, and is terminated by a single nail. The posterior 

 extremity is furnished with three toes, and is much more normal in 

 form than the arm. The pelvis is apparently fairly developed. 



