ACCOUNT OF BOOKS. 



435 



lent exertions of the ideas of the 

 mind are employed for the same 

 purpose, which constitutes madness. 

 The principle, on which relief in all 

 these cases is obtained, is by ex- 

 pending a portion of the sensorial 

 power on such motions and exer- 

 tions. 



S. 55. relates to dlftases of associ- 

 ation. In explaining sympathy, or 

 consent of parts, the doctor consi- 

 ders a tribe or train of actions as 

 divided into two parts, one of which 

 consists of the primary or original 

 motions, the other of the secondary 

 or sympathetic. The different and 

 even opposite modes, in which one 

 of these trains may affect the other, 

 are considered in this section ; and 

 supposed exemplifications of each 

 are adciuced. It may be easily ima- 

 gined that the speculations, in which 

 the author indulges on this subject, 

 are not among the least abstruse 

 and subtile. 



S. 36. On the periods of diseases. 

 Intermission and recurrence in mus- 

 cular actions naturally proceed from 

 the exhaustion and accumulation of 

 sensorial power. These changes, 

 combined with the periods of our 

 diurnal habits, or of heat and cold, 

 or with the solar and lunar periods, 

 are the causes of the periods of 

 fever-fits. A variety of instances 

 are given of the solar and lunar pe- 

 riods of diseases ; and the doctrine 

 of critical days is, by hypothesis, 

 connected with this' iiifluence. 



S. 37. treats of digestion, secretion, 

 and nutrition. The chymical laws 

 of accretion and increase gecni to 

 our author inapplicable to animal 

 bodies, whence he looks for them 

 in the laws of aiflfeation. The 

 lactea'8 abfovb the cliyle, and the 

 glands and ports the nutritious par- 

 ticles be'cj:gii!g t'j them, by auimal 



selection or appetency, put into 

 action by stimulus. The whole 

 animal solids, having been originally 

 formed of the extremities of nerves, 

 require an apposition of particles of 

 a similar kind for their nutrition, 

 which are probably applied during 

 the elongation of the filaments. 

 Old age and decay proceed from 

 the want of irritability. 



S. 38. treats of the oxygenation of 

 the blood in the lungs, and in the 

 placenta. The author adopts the 

 opinion of those who suppose that 

 the blood in the lungs receives oxy- 

 gene from the air ; and also that 

 the placenta is a sort of respiratory 

 organ, furnishing oxygene to the 

 blood of the foetus. The arguments 

 for this latter opinion are derived 

 from the thesis of Dr. James Jeffray 

 and Dr. Forester French. 



Generation is the subject of sect, 

 39. So many ingenious men have 

 already lost themselves and bewil- 

 dered their readers in their conjec- 

 tures respecting this mysterious 

 function, that it would be extraor- 

 dinary if a new guess should solve 

 its difficulties. A very slight sketch 

 of Dr. D.'s notions on the subject 

 will probably satisfy rtiost of our 

 readers. He imagines that the em- 

 bryo is the produce of the male 

 alone, and that the female only gives 

 its lodgment and nutrition. He 

 does not, however, suppose its first 

 rudiments to be a miniature of the 

 future animal, but merely a simple 

 hving filament, which receives all 

 its parts by accretion. This fibril, 

 dropping among the nutritive par- 

 ticles prepared by the female, ia 

 stimulated to action; ar.d, bending 

 into the form of a ring, embraces 

 one of these particles, and coalesces 

 with it. This new organization 

 acquires new irritabilities, chooses 



F f 2 or 



