Document qvDnXLV98BmDv05r7KkwY4qK

July .26, 1940 Dr. C a M. Hillenbrand Hax'riaon. Radiator Division General Motors Corporation Lockpor t, Rev; ^ork Dear Doctor Hillenbrand: .' - I have gone over the exchange of correspondence between you and Dr. Gradwohl coneerning the quesuion of stippling. I have also noted the comparison.of the report's .from Dr. Gr adwohl'3 la 00r ator y ,an d your own Lockport 1a:>ora tory I am returning all of the correspondence and reports to you hero with. It would seem to me that the significance of this discussion Is fairly well . demonstrated oy the; comparison of the two reports, You are able to express your findings in quantitative terms which have a comparative significance., while Dr. ' Gradwohl's reports, ,on the other hand, are in symbols to which certain arbitrary..interpretations -can be given, I believe It is quite clear that Dr, Gradwohl's method of approach can not produce anything better than rough : estimates, and it Is net Sufficiently precise in its ; quantitative expression to be of real value either from the point of view of medical control or medico-legal consideration . :. * s I have stated to you be fore, the thick drop method ox making smears has a certain advantage in enabling one to see a large number of ervthro cytes at one time. It has the unfortunate disadvantage that one does not see as clearly and is, therefore, in some doubt as to the significance of what he sees. There is the further disadvantage that It is impossible to estimate with even approximate accuracy the number of erythrocytes which occur in a microscopic field, For this reason th^re can never be any quantitative expression of the results, and in as much as quantitative expressions are necessary both for Interpretation and for medical-lega purposes, the method may be put down as definitely un satisfactory and inferior to the one which you are using. As far as staining is , concerned!, the Giemsa stain can be used, but I think Wright-*a stain is preferable and I believe methylene blue, as we have used it, is also superior' These are mere details and undoubtedly experience in the use of various stains can be wholly satisfactory. The chief objection to the thick drop method lies in one's inability to express the results in even roughly quantitative terns, and if one is to rely upon guess work in this field, I should think that he might just a3 well guess without doing any work as to have to continue to guess after carrying out laboratory pro cedures. . . By this I do not mean to indicate that thick drop smears are entirely valueless for diagnosis purposes. C-n the other hand it is almost entirely valueless for the purpose for whi ch you want. to. use bleed examinations. . I was very, glad to see you again and to find out how well your ..work had been going 'on. I trust it will continue to go along :satisfactorily. regards, X am. With kindest personal Cordially yours, PM is Rob er t A , Kehoe, M .D . KE 0003670