ACTION OF ALCOHOL UPON CIRCULATION— WOOD AND HOYT. 55 



ords of these experiments were lost. The tracings had, however, beeu studied, and the conclusion 

 reached that no constant effect was demonstrable in them as produced by alcohol, except that 

 very large doses of alcohol depressed the heart. It has seemed to us, as the result of our experi- 

 ments, that the Kroneker apparatus is not applicable to the study of problems like that which 

 we are considering, namely, whether a certain drug does or does not increase the heart work. 

 Under the best conceivable circumstances the isolated frog's heart is under conditions which are 

 unnatural, and which may seriously affect the influence of drugs upon the viscus. In most of 

 our experiments with Kroneker's apparatus, owing to the canula being inserted not into the 

 aorta but into the ventral or dorsal portion of the auricle, the ligature was so low down as to 

 compromit the ganglia lying in the lower third of the auricles, so that the preparation was 

 practically an apical one. The difference between such a preparation and that of the heart 

 proper is shown by the fact that whereas the frog's isolated heart ought to beat from 25 to 40 

 heats a minute, in our experiments with the Kroneker apparatus in most cases it beat 4 to 5 

 times a minute, and often would not rhythmically pulsate at all unless artificial stimulation was 

 applied to it. 



It is true that in some cases we succeeded in tying above the ganglia, under which circum- 

 stances the preparation was one of the heart itself and not an apical one. and the viscus could 

 heat rhythmically. It is evident that with an apical preparation it is not possible to- satisfactorily 

 study a drug which may act upon the heart ganglia, and in any series of experiments with the 

 Kroneker apparatus confusion is liable to arise from an attempt to compare the results of 

 experiments in which the preparations have been really diverse, some with and some without 

 uninjured cardiac ganglia. Of course, exactness on the part of the experimenter will minify 

 this possible source of fallacy. 



Moi'e serious objections to the Kroneker apparatus for use by the pharmacologist are the 

 following: 



First. To maintain the slow circulation of the blood through the loose tissues of the frog 

 very little force is required,, so that the batrachian heart is arranged for and accustomed to but 

 little resistance to its efforts: in the Kroneker apparatus, during the period of record, the heart 

 is heating against a comparatively heavy column of mercury, and is therefore under unnecessarily 

 unnatural conditions. 



Second. An objection which applies equally to the usual forms of the Williams apparatus as 

 to the Kroneker, is the difficulty of interpreting the graphic results. In the interpretation of the 

 writing the height of the wave is usually taken as the measure of the heart work; it is plain, how- 

 ever, that this height is chiefly the measure of the force of the current, since it is entirely possible 

 that the heart should not thoroughly empty itself in systole against the resistance of the mercu- 

 rial column: further, it is certainly conceivable (in our opinion must be) that a heart, w T hich during 

 diastole is only partially dilated and therefore at the time of systole has in it comparatively 

 little blood, may by a sudden, sharp, very complete contraction raise the mercurial column higher 

 than, or at least as high as, it would be elevated by another heart which dilating very freely beats 

 with a slow, prolonged, hut not very forcible, contraction. In one case the graphic result would 

 he a high, narrow cone: in the other case it would he a broad, perhaps flat-topped, wave. The 

 second heart might he doing much more work than the first, although the ordinary method of 

 reading the graphic results would assign to the first heart the victory of doing the larger work. 

 In other words, it seems to us plainly possible that a drug may greatly increase the work done by 

 a heart without proportionately increasing the power of that heart to overcome resistanceand to 

 raise a column of mercury. 



Third. A source of fallacy with the Kroneker apparatus is the varying condition of the heart 

 as to its blood supply: this is readily appreciated by reference to the following tig. 1. It will 

 he seen at once that when the stopcocks L and F are open the blood flows from burette B to 

 burette A, and the heart has through it a regular circulation: when, however, a record is 

 to he made the stopcocks L and F are closed, so that the heart is beating against the resistance 

 of the mercury column, and has no blood passing through it during the record period. After 



