114 Veterin a ry Medici?i e . 



plunging forward, starting to one side, or rearing up and falling 

 back. 



Lesions. The pathological anatomy of this disease is that 'of 

 chronic hydrocephalus. Renault records cases in which the sub- 

 arachnoid and arachnoid fluids were under the normal while the 

 fluid in the ventricles was increased to a marked extent. This 

 accumulation is often so great that the whole of the surrounding 

 nervous matter is greatly attenuated, the convolutions of the 

 cerebral hemispheres are flattened so that the sulci are all but ef- 

 faced, the water may shine through at points and even bulge 

 after the manner of a hernia, the ganglia in the ventricle (corpus 

 striatum, optic thalamus, hippocampus) are flattened and atro- 

 phied, the base of the cerebrum is thinned and bulges downward, 

 and the olfactory lobes may have their internal cavity greatly 

 distended so that they look like little bladders of fluid. The 

 ependyrna may have lost its normal thinness and translucency, 

 having become thick and opaque, and sometimes its surface is 

 granular and rough. The choroid plexus is congested and 

 swollen with infiltration. The brain tissue adjacent is firmly ad- 

 herent and there is a hyperplasia of its connective tissue consti- 

 tuting a veritable sclerosis. At some points, however, the com- 

 pressed nervous tissue has undergone degeneration and softening. 

 As might be expected from the pressure of the liquid, anaemia of 

 the brain tissue is a marked feature of the morbid condition. 



Other conditions have at times been found in chronic hydro- 

 cephalus. 



Renault found two long tumors each as large as a hen's egg 

 projecting from the dura mater into the cerebral hemisphere. In 

 other cases there have been fibrous thickening of the dura-mater, 

 exudations on the pia mater, and false membranes on the arach- 

 noid (Roll). Chabert and more recent writers have observed 

 cysts and tumors of the charoid plexus in such cases, but these 

 have been met with not unfrequentl}' in the entire absence of the 

 characteristic symptoms of this disease. 



Nature. The affection before us is evidently one in which the 

 majority of the higher brain functions are profoundly depressed 

 or debilitated, and this is accounted for by the accumulating 

 intraventricular liquid pressing on the ganglionic centres in the 

 cerebral hemispheres, and in the floor of the lateral and third 

 ventricles. 



