Apart from the interest attached to the explanation of an every-day process, researches such as these are sure in the end to lead to results of direct practical utility. Little by little we are getting to understand that no process of fermentation or putrefaction can be truly called “spontaneous.” They are as much the result of sowing as a thistle that turns up in a field where it was not purposely planted; and just as we can keep our agricultural crops in order by due attention, so crops of ferments can be controlled, the valuable ones being cultivated, and the pernicious weeds sterilised. Methods are known to the vinegar maker by which he can rear, when he needs it, unmixed crops of _Mycoderma aceti_ to ferment his liquors; and the high-class brewer already uses the microscope to ascertain the healthiness of his yeast plant and its freedom from bacteria. May not even cheesemaking, then, be raised from an empirical art into a science, and each cheese factory of the future devote itself knowingly to the cultivation of its own appropriate fungus, learning its likes and its dislikes, and the enemies that have to be contended with? Even the mould sowing of the Roquefort peasants might be improved upon, and pure crops of ferment be raised to inoculate our cheeses. Granted that even then our finest cheeses would not be made better, yet the possibility of raising all cheese to the highest standard of quality of which it is capable is surely sufficient to claim for the scientific experimenter respect and encouragement. In France there are a variety of cheeses which vary in consistence, constitution, flavour, and ability to keep, and these differences are rather owing to the process of manufacture than to the nature of the soil or the peculiarity of climate. The various denominations applied to them, too, indicate differences in manipulation rather than any change in their matter. Nevertheless, we are far from partaking of the opinion of those who deny that both sun and soil have any influence; for as with wine and cider, so with butter and cheese, the pasture has a marked action upon aroma and quality. If we consider the general manner or process of manufacture, we find that it comprehends five distinct operations, which in France are called: 1st, _coagulation du lait_, or the formation of the curd; 2nd, _rompage_, or breaking up of the curd; 3rd, _égouttage_, or drainage, which is accompanied in some cases by _pressage_ or pressing; 4th, _salaison_, or salting; and 5th, _fermentation_, or maturing of the cheese. It is in the various methods, many of which differ very little from each other, and in all of which these operations are in force, but carried out under different conditions, that it is found possible to make 40 or more varieties of cheese, which are divided into 4 categories; 1st, fresh soft cheese; 2nd, salt ditto ditto; 3rd, firm or medium-pressed ditto; 4th, cured cheese, more or less hard and pressed.