PARRY. 28r led to practical results always doubtful, and gene- rally injurious. In the midst of these difficulties, he was induced to examine the effects of the cir- culating system, in its relation to many obscure morbid affections of the brain and nerves. In this system, he perceived a frequent and palpable origin of that irritation which became an imme- diate cause of many nervous affections ; and from the management of the same system, derived a new and more available means of relief than could be obtained under the common doctrines and practice. The first notice of Dr. Parry's observa- tions on this subject appears in the Memoirs of the London Medical Society, for 1788, in an Essay to which their silver medal was adjudged. This paper contains the first hints of a theory, which it was the author's intention subsequently to develope, at great length, on the subject of what has been called " determination of blood " to va- rious parts of the system : with a more particular reference to its effects in the production of diseases of the head, and of all those affections which are denominated nervous. This doctrine became the constant object of his attention, and while it guided his practice, formed also the point towards vv^hich were directed his collections of facts and histories. On the same subject he addressed a letter to the editors of the Analytical Review, and in the Monthly Magazine of May and June, 1798, vindicated his opinions against the arguments of Mr. John Bell, in his General System of Anatomy. Pursuing the same views, he published a paper in the Philosophical Transactions of 1811, on the Effects of Arterial Compression; and, in 1815,
