at about twelve to fourteen days,[52] a softening of the curd is first directly detectable under the rind. This is preceded by the disappearance of the acidity of the curd, which progresses inward. The softening of the curd follows closely the lowering of the acidity. Thus a litmus test taken along the cut face of a Camembert cheese at any stage of softening will always show a sharp acid reaction in the solid sour portion which changes to alkaline just before the softening due to proteolytic action becomes noticeable. These two changes appear to be due to enzymes secreted by the mycelium of the _Penicillium Camemberti_ and _Oidium lactis_ which constitute the most active factors in the ripening. Some accessory bacterial action is indicated but of minor importance in the changes found. To avoid loss from breaking, after the softening of the curd has fairly begun, the cheeses must be removed from the coarse matting to smooth boards where they are watched and turned repeatedly, or as in the more common practice, wrapped at once in parchment paper and boxed. The ripening may be completed in either way. The conditions necessary are such as to favor the extension of slimy areas of bacteria over part or all of the rind to the exclusion of further development of gray-green fruiting areas of mold. Complete softening may occur in three weeks in cheeses in which evaporation has gone on too slowly. Such cheeses are found to contain 51 to 55 per cent of water when ripe and decay very quickly. If handled properly, the water-content should fall from about 57 per cent at the beginning of ripening to 48 per cent at its completion which should require a minimum period of about four weeks. It is more desirable that a cheese four weeks old show a thin core of sour curd in the center than that it be entirely liquid at that age. [Illustration: FIG. 21.--Very soft Camembert cheese.] +150. Composition.+--Properly ripe Camembert shows about the following range of composition: Water 47 to 49 per cent; fat 25 to 28 per cent; protein 18 to 21 per cent; salt 2.2 per cent to 2.8 per cent. Variations outside these limits are usually associated with less desirable qualities. The approximate limits and characters outlined for Camembert still leave a considerable latitude for variations in practice which characterize the output of particular factories in a producing group. At one extreme are brands of Camembert cheese which are very soft (Fig. 21), some of them actually liquid when ripe, and which have very strong odor and taste; one such brand has held first place in the trade of certain American cities for years. Another popular brand when fully ripe is well covered with yellow-orange viscid slime[53] but is fairly firm in texture with high flavor; still others show dry moldy surfaces and mild flavors. The product of certain factories is always characterized by the presence and characteristic ammoniacal odor of _Penicillium brevicaule_.