In counting molds, no distinction is made as to whether a small bit is in the field or a large mass. In making a mount for molds, the solids generally tend to stay in the center of the field while the liquid tends to run to the edge. The fields selected may therefore give a high or low result determined by their location. One examiner desiring to favor the manufacturer may select the outer part for most of the fields, while another, making the examination for the buyer, who may wish to make a rejection, may reverse the operation. Some persons modify the directions given by counting only pieces which are one-sixth the diameter of the field, while others use a smaller fraction. It is easily possible to have one clump of mold in one field which will be twenty to thirty times in extent that of another, yet both are given equal value in the final expression. Third. No real relation exists between the organisms counted and decomposition, for mere numbers are not always coincident with putrefactive activity. A pulp or ketchup may be bad and show less than 30,000,000 bacteria, or it may be good and show 300,000,000. Rotting, or decomposition, may depend more upon the cocci and the organisms which are not counted than upon those which are. The only work done in which microscopical and chemical work were reported on the same samples appears in Circular No. 78, Bureau of Chemistry. This was not done upon samples prepared and kept under control, but for the most part upon commercial pulp and ketchup. The results do not show any close relation between the number of organisms and the lactic acid content which is given as the measure of decomposition. Fourth. Bacteria are expressed in numbers per cc, yeast and spores in numbers per 1-60 c mm. Since the counting can be done only in the fluid portion, an error occurs proportional to the number of bacteria in or attached to the tissue which cannot be counted. The error of assuming that numbers of organisms alone are a sufficient index of the wholesomeness of a food product is well illustrated by work on water analysis. The following statement by an authority on the subject is illuminative: “The belief is widespread among the general public that the sanitary character of a water can be estimated pretty directly by the number of bacteria it contains. Taken by itself, however, it must be admitted that the number of colonies which develop when a given sample of water is plated affords no sure basis for judging its potability. A pure spring water containing at the outset less than 100 bacteria per cubic centimeter may come to contain tens of thousands per cubic centimeter within twenty-four to forty-eight hours, after standing in a clean glass flask at a fairly low temperature. There is no reason for supposing that the wholesomeness of the water has been impaired in any degree by this multiplication of bacteria.”[3] ----- Footnote 3: Jordan, E. O. A text-book of General Bacteriology. 1908.