104 



Mr. P. T. Herring. The Effect of 



It has been shown that the rat's uterus responds uniformly to the same 

 extract of pituitary, and that the extent of the contraction varies directly with 

 the strength of the extract employed*. The test is not sensitive to small 

 differences, but a reduction in the strength of the solution of 50 per cent, yields 

 an appreciable diminution in the extent of the uterine contraction. The blood 

 pressure test in the pithed cat, which Elliottf showed to be very sensitive 

 to minute amounts of adrenalin, is also a good method for revealing small 

 differences in the strengths of weak solutions of pituitrin. With such 

 minute doses, the action of pituitrin upon the circulation can be frequently 

 repeated, and the depressor effect which usually results from a second 

 injection, does not occur unless the first dose is a comparatively large one. 



It is inferred, therefore, that there are no gross changes in the amount of 

 pituitrin present in the posterior lobe of the pituitary body produced either 

 by thyroid-feeding or by thyro-parathyroidectomy. 



Cerebrospinal Fluid. 



The cerebro-spinal fluid from each series of animals yielded sufficient dried 

 material to be made into three separate solutions of 1 per cent, each in 

 Einger's fluid. The extracts were tested upon the rat's uterus, and upon the 

 blood pressure, kidney volume, and urinary secretion of an anaesthetised cat. 



The extracts are practically inactive. A slight increase in the uterine 

 contractions was observed after immersion of the uterus in the cerebro-spinal 

 fluid of the thyro-parathyroidectomised cats, but was not a constant phe- 

 nomenon. None of the extracts show any effect upon blood pressure, 

 kidney volume, and urinary secretion other than that which is produced by a 

 similar amount of Ringer's solution alone. 



It would appear, therefore, that there is no appreciable amount of 

 pituitrin in the cerebro-spinal fluid taken from the fourth ventricle, whether 

 from normal, thyroid-fed, or thyro-parathyroidectomised cats. This does not 

 exclude the possibility that pituitrin is occasionally liberated into the 

 cerebro-spinal fluid in the third ventricle. If such takes place, one would 

 expect rapid absorption to occur, and the probability is against the material 

 reaching the fourth ventricle. 



Carlson and Martin| were unable to obtain any pressor effect from the 

 cerebro-spinal fluid of normal dogs. Gushing and Goetsch,§ on the other 

 hand, found that in certain pathological conditions human cerebro-spinal 



* Herring, ' Quart. Journ. Exper. Physiol.,' vol. 8, p. 268 (1914). 

 t Elliott, 'Journ. Physiol.,' vol. 44, p. 374 (1912). 

 X Carlson and Martin, ' Amer. Journ. Physiol.,' vol. 29, p. 64 (1911). 

 § Cashing and Goetsch, 'Amer. Journ. Physiol.,' vol. 27, p. 60 (1910). 



