3l6 FHILOSOPHiCAL TEANSACTIONS. [anNO 1793. 



testines, &c. The defect of heart, not an uncommon kind of monstrosity, 

 proves, that the energy of the arteries was equal to carrying on the circulation, 

 not only in its own body, but also through its own placenta. The deficiency of 

 nerves renders it extremely probable that their use is very small, if any, to the 

 embryo. 



It has been an opinion, entertained by a very acute physiologist, Mr. John 

 Hunter, that, in all cases, a foetus is a very simple animal, as to its internal 

 actions, and the circumstances attending this monster fully confirm his idea. 

 The usual objects of nature in the formation of a foetus are, that it should grow, 

 and that it should be fitted with parts which, though of no use to it then, are 

 essential afterwards. We know that the lungs are of this kind, and it is very 

 likely that the brain and nerves are so too*. The common uses of the nervous 

 powers are, to convey impressions from without, and volition from within. 

 Now a foetus in the uterus is exposed to no external impressions, and is most 

 probably incapable of volition, since it is not conformable to the general wis- 

 dom of nature to give that which, in such a situation, must be useless. The 

 whole growth then, and formation of a foetal body, would seem to depend on 

 the actions of the vascular apparatus, which, if we may be permitted to judge 

 from this instance, is fully equal to the task. With regard to the manner in 

 which this monster was supplied with nourishment, and with the benefit of air, 

 there is nothing remarkable; because it had a placenta, and the circulation be- 

 tween it and the mother was the same as in the most perfect foetus. 



XIV. Description of an Instrument for ascertaining the Specific Gravities of 



Fluids. By John Godfrey Schmeisser. p. l6-J. 

 ' This whole apparatus is represented in pi. 3, fig. 5, &c. It consists of a 

 flat-bottomed glass bottle (fig. 6) in which is fitted, by grinding, a glass stopper 

 having a thermometer passing through it, (fig. 7.) The bore of this stopper is 

 conical, (fig. 8,) and the thermometer has a glass collar, (fig. g,) which is 

 ground into the bore of the stopper, so as to be perfectly tight. There is some 

 difficulty both in making the glass collar, and in fitting it into the stopper. If 

 the thermometer-tube and the collar be not made of the same metal, the collar 

 is very apt to fly off in grinding; for this reason Mr. S. sometimes fixed the 

 tube into the stopper by means of a thin piece of elastic gum, wound very tight 

 round the tube. This gum, by its elasticity, effectually excludes air and liquids, 

 and is, in the usual temperature of the atmosphere, not dissolved by any liquor, 



* That there is a very material difference between the internal functions of a fcEtus in the womb, 

 and those of an infant after birth, seems very presumable ; not only from finding tliat it can carry ou 

 life without parts which are of the greatest moment afterwards ; but also from its possessing parts 

 which after birtli go into decay, or disappear, as the tliymus gland, &c. — Orig. 



