NERVOUS SYSTEM. (NERVOUS CENTRES. ABNORMAL ANATOMY.) 720c 



scopical examination, which discloses the cha- 

 racteristic pus globules with little or no liquor 

 puris, and by mixing some of it with liquor 

 potassae, when it becomes converted into a 

 viscid material resembling white of egg. 



Pus in the brain is frequently of a green 

 colour, and very commonly exhales an ex- 

 tremely fetid odour. 



The cerebral matter around the purulent col- 

 lection is either somewhat indurated or it is in 

 an oedematous state, or in one of inflammatory 

 softening. When in this latter state the ab- 

 scess is not so defined ; the softened cerebral 

 matter around it is broken up and mingled 

 with pus; this, however, is rare. 



An abscess of the brain may open upon the 

 exterior and so evacuate its contents. This 

 may occur either into the nose through the 

 cribriform plate, or into the tympanic cavity or 

 the external auditory meatus. It is sometimes 

 difficult to determine whether inflammatory dis- 

 ease had arisen in the ear, extending to the brain 

 and exciting the formation of abscess, or whether 

 the abscess already formed in the brain had not 

 burst into the ear. A cerebral abscess may 

 empty itself into either of the ventricles. 



Abscesses are most commonly found in one 

 of the cerebral hemispheres, or in the cerebel- 

 lum ; they are very rarely met with in other 

 parts of the brain. Sometimes collections of 

 pus form upon the surface of the brain between 

 the pia mater and the grey matter of the cere- 

 bral convolutions. And pus or puriform mat- 

 ter is frequently found between the arachnoid 

 and pia mater, where there has been inflamma- 

 tion of either or of both those membranes. This 

 is most common in children. 



Hyperamia and Aneemia. An organ so 

 largely supplied with blood as the brain, is 

 liable to variations in the amount of that sup- 

 ply under various circumstances. It is unne- 

 cessary to recapitulate here the arguments 

 already adduced to show that the opinions of 

 those who maintain that the quantity of blood 

 in the brain cannot vary, is erroneous. Indeed 

 it is much to be wondered at how persons 

 accustomed to inspect the brain post mortem 

 could have adopted such a doctrine. 



In the greatest degree of hyperaemia of the 

 brain, all the vessels of the organ are full ; 

 the veins which lie between the convolu- 

 tions are full ; the vessels of the pia mater are 

 fully injected. Often there are diffused extra- 

 vasations through the areolae of this membrane, 

 causing a red blotch over more or less of the 

 surface of the brain. The grey matter of the 

 convolutions is extremely dark in colour, and 

 if a small portion of it be examined under the 

 microscope the minute vessels which abound in 

 it are found distended with blood. On the sur- 

 face of a section of the white matter numerous 

 bloody points are found, being the orifices of 

 vessels cut across. These points are sometimes 

 very large; sometimes they are surrounded by 

 small extravasations of blood, proceeding from 

 the rupture of some small vessel. In this state 

 of the brain the vessels of the choroid plexus 

 and of the velum interpositum are very full, 

 and also those of the dura mater. 



Cerebral hyperaemia is generally caused by 

 some obstruction to the free return of the blood 

 to the right side of the heart. Hence we see it 

 always after death by asphyxia, and very com- 

 monly in cases of disease of the heart. When 

 the breathing has been seriously impeded just 

 before death, there will always be considerable 

 hyperaemia of the brain. Hence in judging of 

 the nature of a cerebral hyperaemia, the anato- 

 mist may be materially assisted in coming to a 

 correct conclusion if he can ascertain the cause 

 of death and the symptoms immediately pre- 

 ceding it; a fact which clearly denotes how 

 little is the value of mere dissection of morbid 

 parts, unassociated with some knowledge of the 

 symptoms manifested during life. 



In the bodies of persons dead of epilepsy, 

 during or immediately after the epileptic fit, 

 there is always cerebral hypersomia. In these 

 cases the hyperaemia is due to the retardation 

 and obstruction of the venous circulation, occa- 

 sioned by the convulsive struggles of the pa- 

 tient and the resulting impediment to respira- 

 tion. It may be caused, likewise, by an in- 

 creased attraction of blood to the organ taking 

 place at the moment of the occurrence of the 

 fit. For the same reason, whenever death is 

 ushered in by convulsions, the brain will be 

 found in a state of congestion, the amount of 

 which will vary with the quantity of blood in 

 the body. Whatever may be the condition of 

 the brain prior to the epileptic paroxysm, it is 

 always in a more or less congested slate during 

 and immediately after it. The too prevalent 

 notion that cerebral congestion is the cause of 

 the epileptic paroxysm has but little foundation, 

 while there is abundant evidence to prove that 

 the epileptic paroxysm may give rise to cerebral 

 congestion. It is well known that animals 

 bled to death die in convulsions ; and many 

 cases of puerperal convulsions are clearly 

 caused by excessive loss of blood resulting 

 from parturition. 



Hyperaemia of the brain is frequently found 

 after death from depressing and exhausting 

 maladies, typhus fever, &c., all diseases of the 

 low typhoid type, and in cases of general 

 paralysis. The powers by which the circulation 

 is carried on in the vessels are greatly depressed, 

 and the blood accumulates in them, especially 

 in the veins. 



I know of no means of distinguishing active 

 from passive hyperaemia, excepting probably 

 that the capillaries may be more injected in the 

 former, and the veins more filled in the latter. 

 To enable the anatomist to make a correct dis- 

 tinction, the detail of symptoms during life must 

 be called to his assistance. 



Ana-mia. This condition, the opposite to 

 that last considered, is very common. It is 

 frequently met with in children, and in such 

 cases is accompanied with more or less of 

 serous fluid, either in the subarachnoid space 

 or within the ventricles. The brain of the ill- 

 nourished strumous child is generally an anaemic 

 brain. 



Anaemia of the brain occurs when death has 

 been caused, whether quickly or gradually, l>v 

 the loss of blood. It is also present when thu 



