The fluid dropping from the ureter contained more urea than did the blood.  That fluid was therefore no filtrate, but a secretion.  An enhancement of the pressure of the blood flowing through the kidney had no influence on the quantity of the secretion passing away.  An increased rate of movement on the part of the blood, on the other hand, increased in equal degree the quantity of urine.  On a solution of common salt or of mere serum sanguinis being poured through the kidney, no secretion followed.  All these facts, involving the exclusion of the possibility of a central influence being exercised from, the heart or from the nervous system on the kidneys, were deemed by the speaker arguments proving that the urine was secreted by the renal epithelial cells.  A series of diuretics was next tried, in order to establish whether they operated in the way of stimulus centrally on the heart or peripherally on the renal cells.  Digitalis was a central diuretic.  Common salt, on the other hand, was a peripheral diuretic.  Added in the portion of 2 per cent. to the blood, it increased the quantity of urine eight to fifteen fold.  Even in much less doses, it was a powerful diuretic.  In a similar manner, if yet not so intensely, operated saltpeter and coffeine, as also urea and pilocarpine.  On the introduction, however, of the last substance into the blood, the rate of circulation was accelerated in an equal measure as was the quantity of urine increased, so that in this case the increase in the quantity of urine was, perhaps, exclusively conditioned by the greater speed in the movement of the blood.  On the other hand, the quantity of secreted urine was reduced when morphine or strychine was administered to the blood.  In the case of the application of strychnine, the rate in the current of the blood was retarded in a proportion equal to the reduction in the secretion of the urine.

The speaker had, finally, demonstrated the synthesis of hippuric acid and sulphate of phenol in the excided kidney as a function of its cells, by adding to the blood pouring through the kidney, in the first place, benzoic acid and glycol; in the second place, phenol and sulphate of soda.  In order that these syntheses might make their appearance in the excided kidney, the presence of the blood corpuscles was not necessary, though, indeed, the presence of oxygen in the blood was indispensable.

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VARYING CYLINDRICAL LENS.

By TEMPEST ANDERSON, M.D., B. Sc.

The author has had constructed a cylindrical lens in which the axis remains constant in direction and amount of refraction, while the refraction in the meridian at right angles to this varies continuously.