350 Mr. A. E. Tutton. Thermal Deformation of the 



The experiments confirm those recorded in the preceding section. 

 Abdominal compression raises the vena cava pressure, and so leads to 

 increased cerebral capillary pressure, and in this way to increase in the 

 volume of the cerebro-spinal fluid secreted. Increase of volume, as 

 before, is accompanied with fall in the percentage of solids present. 



Intro-vascular Injection of the Cerebro-spinal Fluid. 



One of us (W. D. H.), in conjunction with Dr. Mott, F.R.S., has 

 been for some time engaged in examining the results of injecting into 

 animals cerebro-spinal fluid removed from cases of brain atrophy, 

 especially from cases of general paralysis of the insane. This fluid 

 contains a toxic substance, choline, doubtless derived from the dis- 

 integration of lecithin in the brain. Injection of such fluid into the 

 jugular vein of animals (dogs, cats, rabbits), anaesthetised with ether r 

 causes a marked lowering of arterial blood pressure, which is partly 

 cardiac in origin, but principally due to the local action of the poison 

 on the neuro-muscular apparatus of the peripheral vessels, especially in 

 the splanchnic area.* 



The fluid obtained from the present case was also injected in a 

 similar way. Quantities varying from 7 to 10 c.c. were injected into 

 the circulation in dogs, but with entirely negative results. Such a 

 quantity in the case of fluid from a general paralytic would be quite 

 sufficient to cause a marked fall of arterial pressure. 



Similar negative results, both as regards blood pressure and respira- 

 tion, were obtained with other specimens of normal cerebro-spinal fluid 

 removed from other animals, or from cases of meningocele and hydro- 

 cephalus in children. In all such cases, also, choline was searched for 

 chemically, but with negative results. 



" The Thermal Deformation of the Crystallised Normal Sulphates, 

 of Potassium, Rubidium, and Csesium." By A. E. TUTTOX,, 

 B.Sc. Communicated by Captain ABNEY, C.B., F.R.S. 

 Received January 31, Read February 16, 1899. 



(Abstract.) 



In this memoir are communicated the results of sixty-four determi- 

 nations of the thermal expansion of the orthorhombic crystals of the 

 normal sulphates of potassium, rubidium, and caesium, carried out for 

 the three axial directions of the crystals with the aid of the compen- 

 sated interference dilatometer previously described by the author.! 



* 'Physiol. Soc. Proc.,' Feb., 1897, and Feb., 189S (' Jouru. of Physiol.,' yols. 

 21 and 22). 

 f ' Phil. Trans.,' A, rol. 191, p. 313. 



