We have not given specific names to these different ferments, any more than we have to the other microscopic organisms which we have had occasion to study. This was not from any disregard for names, but from a constant fear that, since the physiological functions of these minute forms was the exclusive object of our study, we might be led to attach too much importance to exterior characters. We have often found that forms, having nothing apparently in common, belong to one and the same species, whilst similarity of form may associate species far apart. We shall give some fresh examples of this fact in the present paragraph. A German naturalist, Dr. Rees, who has discovered new proofs of the diversity of alcoholic ferments, putting aside, perhaps rightly, such scruples, has attached specific names to the different kinds of ferments, in his _brochure_ published in 1870, which we have already cited (p. 71). Indeed, we have often ourselves, for brevity’s sake, made use of the names proposed by Dr. Rees.[84] [Illustration: Fig. 27.] In a Note inserted in the _Bulletin de la Société chimique de Paris_, in 1862, we figured a ferment of small dimensions, which develops spontaneously in must, filtered or unfiltered, and which is very different from the ordinary ferment of wine. It is the first to make its appearance in the fermentation of the grape, and may even appear alone if the must has been previously well filtered, doubtless because its germs, being smaller than those of other ferments, pass through the filter more easily and in greater number. Fig. 27, extracted from our Note of 1862, represents this ferment, together with some spherical cells of _high_ yeast, with the object of giving a more exact idea of the relative dimensions of these two ferments and their dissimilarities. Dr. Rees has named it _saccharomyces apiculatus_. The same savant has given the name of _saccharomyces pastorianus_ to the yeast of the secondary fermentations of sweet liquids, such as wine that has remained sweet after its principal fermentation. We have described this yeast in a Note published in 1864, on the diseases of wine, from which we give the following extract:—[85] [Illustration: Fig. 28.]