APPENDIX 339 



in 15 to 20 cubic centimetres of sterile freshly distilled water. 

 This may be injected intravenously, using an appropriate 

 syringe, or preferably it is filtered through cotton into the 

 burette and diluted up to 150 cubic centimetres, using a 0.4 

 per cent, saline solution or freshly distilled water. In the 

 case of neosalvarsan, since the quantity of solution is only 

 one-half that of salvarsan, it is allowed to enter the vein in 

 five minutes. In ail other respects the technic of administra- 

 tion differs in no way from that described for salvarsan. 



Intraspinal Administration. — It was soon recognized 

 after the advent of salvarsan that its administration intra- 

 muscularly or intravenously in certain forms of syphilitic 

 disease of the nervous system was not so effective as in 

 other manifestations of the disease. This observation was 

 confirmed by the Wassermann reaction, inasmuch as the 

 reaction of the spinal fluid in certain neurological cases per- 

 sisted positive long after the reaction of the blood-serum 

 became negative. Moreover, it is a common observation to 

 find in S3'philitic neurological patients a negative blood and 

 a positive spinal fluid Wassermann or a weakly positive blood 

 reaction and a medium or strongly positive spinal fluid result. 



Communication between the lateral ventricles of the brain 

 and the subarachnoid spaces of the brain and spinal cord 

 exists through the foramina of Magendie and Luschka. 

 The nervous choroid plexuses and the velum interpositum, 

 possibly assisted by the blood-vessels of the meninges, act 

 as the chief dividing plane or filtration plant between the 

 blood and the spinal fluid. Owing to the fact that the 

 specific gravity of the blood is greater than that of the 

 cerebrospinal fluid, also that the pressure of the cerebro- 

 spinal fluid is greater than that of the intracranial venous 

 blood, osmosis takes place in the direction of the venous 

 blood. This fact may account for the failure of salvarsan, 



