1) Laying emphasis on chemical equation of Jolles's reaction, and systematically examining those causes for mismeasurement happened during urinal determination of indican, I was enabled to find out certain new microestimating method for indican, which would prove somewhat satisfactory. 2) As indicated below, the normal value of urinal indican estimated by new method, have acknowledged certain marvelously high values that have far superseded those theories hitherto known. However, I am to recognize the Principle No. (2) i.e., the quantitative value for indican that was considered to have as its object the colour reaction against the fuming hydrochloric acid, which could purely has enabled to induce it solely into the Thymolindogenide; while, Principle No. (1), i.e., the quantitative value which has for its object the original color of Thymolindogenide, should be recognized as total Indican value, i.e., that was enabled to be induced into every kinds of Indogenide including the very Thymolindogenide: ① Normal amount (mg) of excretion Within 24 hours. highest 158.0 (Principle No.(1))～137.0 (Principle No.(2)), lowest 42.5 (〃 〃)～29.8 (〃 〃), average 98.0 (〃 〃)～77.0 (〃 〃). ② Normal density mg % highest 22.7 (Principle No.(1))～19.7 (Prnciple No.(2)), lowest 2.5 (〃 〃)～1.8 (〃 〃), average 9.3 (〃 〃)～7.5 (〃 〃). ③ Misestimation in quantitative value shown by Principle No.(2) to that of Principle No.(1) is estimated as + 2.2～ -43.0% ; average, -26.7% . 3) Various stimulants to give rise to mismeasurement on the side of indican at its quantitative determination that have been able to investigate, were as follows. ① The condensation between the thymol and indoxyl in the urine increasing at a gradual ratio, and the quantitative value shows a proportional increase as time for reaction lengthens; yet, if the reagent due to Takeuchi (Estimating method (1)) should be used, it may come to an end after two hours' reaction. ② The descent in estimation owing to a shortening of reactionary time may roughly be ascribed to the fact that while the condensation between the thymol and indoxyl remains incomplete, the formation of indigo undergoes certain stimulas. ③ If one might consider the certain of Jolles's reaction as a principle for indican estimation, it would be told as very unsatisfactory in fact, even after 2 hours of reaction, already it has been seen to have given rise to so marked a difference as -51～ -71% . Altogether, the chief cause will be pointed out as the incomplete oxidation owing to Obermayer's reagent. ④ Order in adding chloroform according to Endo's method, assists to formulate Indigo, but in the same degree affects to decrease to formulate the Thymolindogenide; so that, in 2 hour's reactionary course, it brings about already -20% misestimation. ⑤ Endo's standard solution, though excellent in its tint, its titer value amount even to 3 or 3.6 times larger than its theoretical value, being remarkably dense. This may take place, perhaps, when he decided on titer, Mr. Endo employed for standard the indican value estimated by Takeuchi's method. ⑥ For an urinal oxidizing agent between the thymol and the indoxyl I might mention that of Mr. Takeuchi as best of that kind. The oxidizing agent indicated by 1% potassium chlorate, 3% hydrogen peroside, 1～5% ammonium persulphate, 4% chlorinated lime, 10% copper sulphate, under the same conditions, only cope with 1/2 power proved by Takeuchi's, at most. Whereas, sodium nitrit cannot stand to be used because apt to produce some nitrosothymol. ⑦ The precipitation rate due to precipitator attributed to urinal indican proves different according to the kinds as well as volume of precipitators. In case 1/10 volume of 20% lead acetate solution or 20% basic lead acetate solution has been added, the precipitation rate proves respectively 26～36.4% or 15.4～31.4% ; in case 1/20 volume has been added only the rate 1/3.5 of the former would be seen. The rate of discovery of precipitated indican nearly corresponds to 83～94% of the entire quantity. ⑧ Extinction curve for the dehydrated chloroform-extract, no matter what kind of test urin, technic, oxydizing agent or precipitator may be emplyed, would come so near the typical curve for Thymolindogenide, yet not so perfectly; the quantitative value due to Principle No.(1) indicating certain indefinite increase, compared to that of Principle No.(2), the cause of which rests with the fact that when the Thymol and Indoxyl in urin condense themselves, though taking care not to formulate the indigo, there will be given birth to certain brown pigment soluble to chloroform, besides the Thymolindogenide. ⑨ When the Thymolindogenide in the urine containing the trichloroacetic acid (urin T.) is estimated, frequent washing of chloroform-extract may be necessary. Or else, the quantitative value indicates an abnormally high value, because of an increase in color tone caused by dehydrated chloroform-extract that has resulted from the increase of urinal trichloroacetic acid; so that one would have a marvelously high value at 80% density. ⑩ The main motive for an increase in estimative value in urine T. is ascribed to those violet or reddish-violet tone that appear within reddishbrown dehydrated chloroform-extract. Its real state might be deemed, not only to depend upon the color reaction effected by Thymolindogenide against hydrochloric acid as well as trichloroacetic acid, but also due to certain color reaction shown by Thymolindo-genide owing to a new appearance of certain ether-like aromatic substance. ⑪ The estimation for urine containing the acetic acid (urine A.) proved that the highest value was reached when urinal acetic acid had indicated about 0.5% density; too much acetic acid found in the urine is apt to make difficult the extraction of the Thymolindogenide due to Chloroform, and leads to lower its value. ⑫ The estimated value for urine T. has proved maximum at about 10% density of urinal trichloroacetic acid; the overmuch amount of urinal trichloroacetic acid, aided by a strengthened color tone maitained by chloroform-extract, rather serves to enhance the estimation. ⑬ The highest value indicated by Thymolindogenide in one and same urine, shows slight difference between urine A and urine T, in the light of principle No.(2); however, as to Principle No.(1); the latter undergoes about 1.5 times increase that of the former. Also, the value for Principle No.(1) against the highest value proved by Prineiple No.(2), amounts to in average 1.3 times in case of the former, but 2.5 times (in average) in the latter. ⑭ The estimation value in urine T. should be corrected owing to a degree of increase. However, that degree tends to become unsteady due to estimating method, principle for the same, density of trichloroacetic acid or washing-method of chloroform extract and so on; so reliability could not be expected. ⑮ The secondary extracted amount of Thymolindogenide for the 1st one which indicated greatest amount has proved, about 20% in case of urine A, 10% in urine T.; the extraction of Thymolindogenide proving better in latter case. ⑯ The estimation mistake shown in Principle No.(1) due to stufenphotometry and colorimetry indicates as about 5% (urine A) and about 10% (urine T) increase in the latter. 4) From the above results as to the causes for misestimation of indican quantity, as well as about normal indican value, it was vindicated that there exists certain strong factors to lower the value in various estimation method for indican where Jolles's reaction deemed as it principle, as well as in such old-fashioned method in which precipitators are used; at the same time, the necessity for re-examination for those various achievement as to clinical significances of urinal indican thus clarified hitherto, by using new method, has become urgent.