TERATOLOGY. 



965 



peculiar and sarcastic wit to this absurd 

 aetiology, and gives the very ludicrous ac- 

 count of a surgeon who supposed that the 

 Sireniform monster had been formed during 

 a very difficult delivery. If it is, on the 

 contrary, an original malformation, it may be 

 asked, what can be its remote cause? Is it 

 the original want of one of the umbilical ar- 

 teries? I should not think so ; for one of these 

 arteries is also wanting in the variety in 

 which all the parts of the t\\o f extremities are 

 present, and we know that one of them may 

 be wanting in a completely well-formed child. 

 (See p. 948.) Another question is, whether 

 si/ntpvdia can be attributed to the coalescence 

 of the inferior extremities (Meckel, Kamm, 

 Boerhave, and Ouveilhier). Neither ara I in- 

 clined to adopt this cause. 



1. I cannot imagine a coalesence of bones 

 so complete, that through these could be 

 formed one single extremity. 



2. It is impossible to explain by it the im- 

 perfect condition of the leg and of the foot 

 in the majority of cases. 



3. From such a fusion or coalescence can- 

 not be derived the imperfect state of the 

 rectum, and of the sexual and uropoietic or- 

 gans. 



It seems to me more probable that sym- 

 podia is due to some original malformation 

 of the pelvis and its viscera, of which the 

 cause remains unknown. The formation of 

 a head solely, of an incomplete trunk without 

 the lower limbs, or of a single inferior ex- 

 tremity, is certainly to be attributed to nothing 

 else but impeded developement. It shows, 

 moreover, that the different parts of the body 

 are quite independent of each other in their 

 original formation. 



e. Original defective formation of the pelvis. 

 In a well constituted body the pelvis may be 

 originally malformed, as is proved by the ob- 

 liquely narrow pelvis of Nazele, and by the 

 transversely narrow pelvis of Robert ; of which 

 malformation the cause is to be found in the 

 imperfect formation of the sacrum. 



f. Defective developement of the spinal 

 column. This has been principally observed 

 in calves. It is too short, defective, more or 

 less incurvated, and some of the vertebrae 

 fused together. The head is situated at a 

 short distance from the thorax ; the tail and 

 the anus are reflected to the dorsal surface ; 

 the pelvis is too narrow, and turned upwards 

 at its posterior part. 



VII. Defective Formation of the Extremities. 



The origin of many malformations of the 

 limbs may be referred to the early periods 

 of embryogenesis. But for some of them this 

 is impossible. 



1. Want of all the extremities is an arrest of 

 developement at that period, in which the 

 limbs are not yet formed, and in which small 

 tubercles occupy their places. Sometimes the 

 superior extremities only are wanting, which 

 urges the inferior extremities to acquire a sort 

 of dexterity by which they may in some mea- 

 sure supply the place of the superior limbs. 



Of all the examples which are known of it, 

 that of Thomas Schweicker is the most me- 

 morable. The inferior limbs only are rarely 



Fig. 624. 



3 ti 3 



