UTRICULAR STRUCTURES. 



IT is now some years since I first imagined that the 

 phenomena exhibited by various bodies occurring in the 

 cell-contents, and supposed to be solid, could only be 

 explained by the hypothesis that they were utricles, having 

 an inclosing membrane with inclosed contents. The 

 minute size of the objects in question, the uncertainty 

 which attributes to the appearances, on account of the dif- 

 ferent refractive power of different substances, and the cir- 

 cumstance that, already, repeated attempts to demonstrate 

 cellular or utricular structures in the cell-contents had 

 failed, impressed the necessity of great circumspection. 

 I now lay before the physiological public my researches 

 on the various forms of the contents in the various kinds 

 of cells, only after extensive observations, and a confir- 

 mation of them by a comprehensive critical inquiry. 



Earlier and more recent theories, which declare the 

 cells to originate from starch- or chlorophyll-granules, and 

 from which might be deduced a cellular structure of 

 these granules, may conveniently be passed over as un- 

 founded. 



Earlier authors, likewise, who use granule and utricle 

 as synonymous terms, and imply no distinction between 

 the two expressions, merit no special mention. 



More recently, granules and utricles have been placed 

 in opposition to each other. The first are considered 

 to be solid, the latter hollow. After this definition, 

 the opinion that cells inclose only granules gradually 

 gained the upper hand. Better instruments and more 



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