SUMMARY. Method of volume calculation fur stands within experimental plots of sylviculture studies about forest production and more particularly the ones about treatment methods should be based on the most accurate data. They should be qualitative and quantitative. Therefore, in order to build the tarif tables necessary to volume estimation of stands, P. AYRAL, Leader of the first Section of the Research Station, worked on a method of « stratified sample » whose applicationhas already given excellent results. The most important characters are1) Place of the trees in stories of vegetation (1, 2, 3) ; 2) Crown development (A, B, C); 3) Quality of the stem (D, T, r, etc...). The stratified sample should include sample tree of each class of such characters in every girth class, proportionally with the corresponding number of steins in the stand in order to avoid a systematic distortion. Volume measurements of standing trees necessary to that system, are realized with the « Ecole Forestière » entrainminladder. One must then prepare, with this representative sample, a tarif table, suitable to the stand after its thinning. The practical basis of studies was constitued of seven clear felled stands, most accurately measured, tree by tree, after numeration. Instead of the graphical method, improper by many ways,A1;Ani E has worked on a mathematical method, less subjective andallovfing calculation of the standard-error of volume estimation. Several mathematical laws (as V = f (c)) have been tested (V = volume; c girth at b. h.).The following formula has been adopted: V=a+bc2 whose normal equations are easy to solve and which keeps the standard-error, between 1 and 2 %. The constants a and b are calculated according to the method of least squares. The constants once known, the volume of a stand of N steins is given with the formula: V Na + b ,^ n ; It is practical and even cheaper to have these calculations made by an electronic machine. It will be noted that, if a scale of squares is used for abscissae, the law should be graphically represented by a straight line. Some conclusions, though less general, but very interesting, are to remember: 1) in each considered stand, within the same class of characters. the volume distribution for a given girth is the usual distribution of LAPLACE-GAUSS. 2) for a given girth, there is a very significant difference between the volumes of trees of class I and trees of class 2 for instance. Everything equal besides, there are no differences between the volumes of a tree « A » and a tree « B »...\t last, the quabtative study of stands, considered as necessary for specifying the influence due to methods of treatment, has been undertaken, the methods of investigation, made clear.\ graphic study (diagram) will be started, which will permit to know what simple curve should he calculated. in order to take into account the distribution of the different qualities of products according to the b. 11. girth.