Natural History. 215 



at the same place, where the convulsion was very strong, when 

 the current was passed from the shoulder to the hand. 



Sometimes this difference existed only in one limb. — A woman, 

 who had lost the use of the lower limbs in consequence of an 

 inflammation of the spinal marrow, felt the left foot contract with 

 most force when it touched the negative pole of the pile ; the 

 right foot contracted with equal force, whether it was in contact 

 with the positive or negative pole. This effect appeared to be due 

 to a loss of nervous sensibility in the right foot, so that they had 

 become indifferent to the direction of the electric current. 



If a finger be immersed, as far as the second joint, in water* 

 connected with the positive pole of a battery containing twenty- 

 five or thirty pairs of plates, and the circuit be completed by 

 touching the negative pole with a metallic cylinder, held in the 

 other hand wetted, a shock is felt in the finger, not extending 

 beyond the second joint j if the direction of the current be reversed, 

 the shock is felt in the third joint. Upon giving attention, it will 

 be found that the first shock is more external, and accompanied 

 by a distressing sensation ; whilst the second shock is more deeply 

 felt, and is accompanied by no particular sensation at the place 

 where the finger touches the water. The effects are accounted 

 for by the supposition that, when the finger touches the negative 

 pole, the simultaneous occurrence of the two convulsions causes 

 the stronger contraction ; and that, when the finger touches the 

 positive pole, the electricity which traverses the nerves proceeds 

 in a direction contrary to their ramification, and, in place of pro- 

 ducing a shock, occasions the peculiar sensation. 



If two metallic cylinders be covered with wet cloth, and one 

 being held in each hand, contact is then made with thirty or forty 

 pairs of plates, moderately active, besides the shocks which are 

 felt each time the communication is completed, there is a parti- 

 cular sensation in the palm of the hand, communicating with the 

 positive pole. This sensation has been very distinct in some 

 persons sensible to the effect of electricity ; and they compared it 

 to that pricking sensation often felt in the hands or feet when the 

 nerves have been compressed for some time together. — Bib, Univ. 

 xlu. 287. 



8. Ossified Brain. — M. C. Matte ucci having examined a brain 

 which he discovered in an old anatomical collection, found it to ex- 

 hibit a singular case of ossification throughout its whole substance. 

 When heated, it'burnt, evolving ammonia, leaving a bulky charcoal. 

 When examined by chemical agents, carbonate of lime was found 

 in small quantity, and phosphate of lime in much larger, but the 

 principal part of the mass was animal substance, closely allied to 

 osmazome. 



The composition of the concretions that are sometimes found 

 in the pineal gland are, according to Fourcroy, of the same 

 nature. — Ann. de Chimie, xlii. 335. 



