UTRICULAR STRUCTURES.

It is now some years since I first imagined that thephenomena exhibited by various bodies occurring in thecell-contents, and supposed to be solid, could only beexplained by the hypothesis that they were utricles, havingan inclosing membrane with inclosed contents. Theminute size of the objects in question, the uncertaintywhich attributes to the appearances, on account of the dif-ferent refractive power of different substances, and the cir-cumstance that, already, repeated attempts to demonstratecellular or utricular structures in the cell-contents hadfailed, impressed the necessity of great circumspection.I now lay before the physiological public my researcheson the various forms of the contents in the various kindsof cells, only after extensive observations, and a confir-mation of them by a comprehensive critical inquiry.

Earlier and more recent theories, which declare thecells to originate from starch- or chlorophyll-granules, andfrom which might be deduced a cellular structure ofthese granules, may conveniently be passed over as un-founded.

Earlier authors, likewise, who use granule and utricleas synonymous terms, and imply no distinction betweenthe two expressions, merit no special mention.

More recently, granules and utricles have been placedin opposition to each other. The first are consideredto be solid, the latter hollow. After this definition,the opinion that cells inclose only granules graduallygained the upper hand. Better instruments and more

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