308 



PHYSIOLOGY 



CHAP. 



88 years of age respectively, showed plain signs of atrophy 

 which were not present in the brain of Menzel, who was 89 

 when he died. 



In connection with the lengthening, twisting, entanglement, 

 and disorder of the blood-vessels, we are confronted once more 

 with the vexed question whether these changes are signs of 

 pathological senility or are in part indicative of the arteriosclerosis 

 which so frequently attacks the old. A series of clinical and 



abed 



Fio. 127. A, Semi-schematic figures showing the mechanism by which the cerebral vessels of old 

 people gradually change from a simple spiral winding to complete loops, d. This process is 

 due to the fact that the vessels are forced to adapt themselves to a space considerably shorter 

 than their own length, in consequence of the atrophy of the tissue and the lengthening of the 

 vessels themselves. The black lines and the arrows indicate the tortuous movement on the 

 longitudinal axis, a movement which corresponds to a complete revolution of the vessel on its 

 own axis for each loop. B, Semi-schematic figure showing the results of the tortuous move- 

 ment of the vessels on their longitudinal axis. (Cerletti.) a, ft, collateral vessel twisted round 

 the parent stem ; c, three terminal branches intertwined ; d, extraordinarily complicated tangle 

 of vessels. 



anatomical investigations of a convincing and decisive order have 

 shown in arteriosclerotic brains and in those of arterio- 

 sclerotic lunatics the presence of patches of damaged tissue, 

 usually of the type of perivascular gliosis (Alzheimer), in addition 

 to the usual centres of haemorrhage and softening ; these patches 

 alternate with and are sharply denned from more or less extensive 

 tracts of cerebral substance which are relatively unimpaired. 

 In pure cerebral arteriosclerosis miliary necrosis is absent. In 

 the physiologically senile brain, on the other hand, the changes are 

 diffuse and affect the whole cortex, and more especially the nerve 



