ANATOMY OF A MONODACTYLOUS FOETUS 391 



elbow, single bone in the forearm and monodactyly, as is shown 

 in both arms of the foetus described by me. This is an impor- 

 tant point as it leads to the assumption that this condition is a 

 ver}^ definite one, which although very rare is not purely a 

 chance occurrence but may have some definite cause. Thus it 

 would be the concrete indication of the previous working at a 

 certain particular period of development of some definite 

 vicious or teratogenic influence. 



RADIOGRAPHS 



Four radiographs were made of the foetus in the X-ray de- 

 partment of the Toronto General Hospital. Plates were made 

 of the whole body from the front and from the side, and also 

 special ones of each arm from the side. The definition of 

 structures in the plates was excellent and identification of 

 various parts was an easy task. Prints made from these plates, 

 however, were unsatisfactory, since heavy prints intended to 

 show structures with light shadows made heavier parts a solid 

 mass of shadow without detail, while light prints did not bring 

 out distinctly the lighter parts. Three prints of each plate were 

 made, a heavy, a medium, and a light, and from these and the 

 plates, the following description has been pieced together. The 

 illustrations are from actual tracings from the plates and are 

 designed to show only essential structures. 



The radiograph of the left arm (text fig. A and fig. 6) shows a 

 well-developed scapula of normal proportions, and articulating 

 with it the humerus, which is fairly heavy and of typical shape. 

 The upper end is well expanded as is also the lower, but as 

 might be expected no ossification is yet present in the epiphyses. 

 The lower end extends almost to the end of the bend of the 

 elbow, and coming off in front of it is a single bone lying in 

 the forearm. Owing to the cartilaginous condition of the epi- 

 physes, no articulation can be demonstrated, only the osseous 

 tissues showing. That this bone in the forearm is the radius 

 is quite evident from its shape, the upper end being narrow 

 and the shaft round above and gradually broadening as it pro- 

 ceeds distally, the entire bone being also slightly curved in 



