President's Address.

SOME SUGGESTIONS CONCERNING THE EXAMINATION OF BLOOD.

By J. H. Linsley, M. D., Burlington, Vt.

Members of the Vermont State Medical Society :

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Section I, Article I of our By-Laws, referring to the duties of the President, contains the following: "He shall deliver, or cause to be read, an address or dissertation on some medical subject at the annual meeting."

In discharging this duty I desire to call your attention to a very few ethical matters before taking up the text proper of this address.

It is a cause for mutual congratulation that the proportion of attendance to the total membership is steadily increasing. Now while this is a very commendable condition, the fact remains that this proportion is still far short of what it should be, ought to be, and would be, if every member would feel the individual responsibility in the Society's success which his signing of the Constitution implies.

Another evidence of increasing interest is the greater willingness on the part of the members to prepare and read

papers at our meetings. But a few years since it was a matter of some considerable difficulty on the part of the Executive Committee to secure papers enough to fill out the programme for two days, but considerable maneuvering is now necessary to see that all papers prepared shall have adequate time for their delivery and discussion. Indeed so pressing has become this lack of time, that I seriously advise longer sessions, preferably by having the meetings extend from 2 o'clock Wednesdays, instead of 10 o'clock on Thursdays, as at present. It may be said in connection that those papers scheduled for presentation at the final, or Friday afternoon session, receive but scant attendance, a circumstance which is discouraging to their writers. I feel confident that this would be remedied by the establishment of longer sessions.

I would also suggest for your thoughtful consideration -in line with the matter of extended sessions-the desirability of the arrangement of the papers under the head of sections.

For instance :

Having all papers on surgical topics read at one day's or half day's session, those on purely medical at another, gynecological at a third, and so on. In this way those of us who were interested in any one line especially, would not be compelled to be in attendance during the entire three-days' session in order to hear such papers of especial interest which might be scattered over the time of the whole meeting.

Again I wish to express my appreciation and gratitude for the effort of those members of our profession who have come from abroad to entertain and instruct us in matters pertaining to their specialties, in the practice of which they are recognized authorities, and to call your attention to the

great advantage, to most of us, in having several metropolitan physicians and surgeons with us at each annual meeting. I believe the adoption of such a course would prove of benefit alike to visitors and members.

"Some

I have selected as the text of this address, suggestions concerning the examination of blood." This theme was chosen for three reasons: First, because I have given attention to the subject for some time; second, its great importance; and third, the very slight consideration given the matter by the average practitioner.

Many physicians are deterred from making blood examinations by the supposed difficulty of technique in the work, and the instruments and paraphernalia necessary for its conduct.

I shall endeavor to show that this conception of the matter is incorrect, and that a vast amount of exceedingly valuable information concerning the condition of our patient can be obtained by the examination of a drop of blood, with no greater outfit than a good microscope, clean coverglass and slide, a little vaseline, a slip of paper, and a steel pen.

First, a cover-glass and slide are carefully cleaned. A piece of ordinary writing paper is then folded into a triangular shape, and after taking up a small quantity of vaseline on the point of the paper, a narrow, thin film of the vaseline is placed around the edge of the cover glass. The end of one of the index fingers is carefully cleansed with water (it is better to employ a nail brush in doing this), and the finger pricked by a sharp, rapid movement of the arm of the operator, the instrument used being either a needle, which has been previously sterilized in a flame, or

a new, sharp-pointed steel pen, one of the points of which has been broken off.

As soon as a small drop of blood has collected, the glass slide is brought in contact with the same, the slide placed on a level surface, and, as soon as possible, the cover-glass placed over the blood-vaseline side downand sufficient gentle pressure made over the cover-glass to produce a contact everywhere between the border of vaseline and the slide. In this simple manner a most effective moist chamber is provided, which is completely sealed by the vaseline, and in which the blood will remain in a suitable condition for microscopical investigation for several hours.

Another method much employed, and especially useful where staining is desired, is the dry process. A clean cover glass is brought in contact with the summit of the drop of blood, obtained in the manner I have described, quickly removed, and a second cover-glass-or the end of a glass-slide-is immediately drawn across the blood, producing a thin, flat layer which drys almost at once. The preparation is then kept for ten or fifteen minutes at a temperature of 110° to 120° C., and is then ready for whatever staining is desired.

Before proceeding, allow me to call your attention, briefly, to the composition of normal blood, and to suggest the absolute necessity of familiarity on the part of the investigator, with the condition and appearance of normal blood.

For present purposes the chemistry of the liquor sanguinis and corpuscles, with the exception of haemoglobin need not be considered. I prefer to deal only with the corpuscular elements.

As you all know, the cells of the blood are of two great classes,-the colored, or red, and the colorless, or white. I prefer the terms "colored" and "colorless" because none of the individual corpuscles are "red," but only a slight shade of amber, or yellow, while the others are devoid of color.

The normal colored blood corpuscle of man is a biconcave, circular disc, having an average diameter of 1-3250 of an inch. This diameter is liable to great variations at least 3 in the same individual, and persons differ very much in the variance in size of their colored corpuscles. In some, the examination of thousands of cells will show no appreciable difference, while in others, the most remarkable variety of sizes is seen. I am not satisfied that this variability in size is of any pathological significance.

The same cannot be said from a medico-legal standpoint. Given a suspected blood-stain, on or about the clothing of an accused, or implements, or utensils supposed to have been used by him at the time of an assault, and the investigator finds but a few colored blood corpuscles, which are, apparently, of the same size as human colored blood-cells; can the physician, however expert, go on the witness stand and conscientiously swear that they are even probably human blood corpuscles? In the light of our present knowledge of this subject, I say he can not. It may be said in opposition to this statement that with proper micrometers the exact size of the corpuscles can be measured. Now it is a fact that only a very expert microscopist can make such a measurement accurately, and even then there is the liability to error as was shown by Ewell.* *System of Legal Medicine. Allan McL. Hamilton, p. 175.