10 Tannin in tJie Fruit of the Persimm on [Sept. 



be considerably greater than it is still later. Mushiness and non- 

 astringency are not constantly associated, as Howard (1906) has 

 maintained ; nor has the progress of the fixation of tannin reached 

 its final goal, even with the last stage of edibility. 



It is the purpose of the present paper to account, from the 

 microtechnical point of view, for these phenomena; to show, namely, 

 that the fixation of tannin during ripening is associated with the 

 presence and, probably, accumiilation of a second colloid (the view 

 already advanced by me) and to discover the relation between solu- 

 ble and insolnble tannin during the progress of ripening. To this 

 end it will first be necessary to obtain a clear conception of the 

 structure of the tannin idioplast, such as has not so far been had, 

 either from Howard's account (1906) or from my own (1911). 

 This physiological type of tannin-cell or idioplast is common to both 

 the date and persimmon, and doubtless to many other structures 

 including fruits (Tichomirow, 1904). But a prolonged study of 

 them in preserved material of the date led me (1910) to no sure 

 light regarding the structure and interrelations of parts in the living 

 tannin idioplast, reliable as the methods employed by me may 

 have been for determining the distribution of tannin in the tissues. 



The present study is based upon fresh material of native and 

 exotic species of persimmons, beginning with fully developed but 

 still hard and wholly astringent fruit, and ending with specimens 

 showing disintegration of the tissues. Fruits treated experimen- 

 tally, with a view to dififerential ripening, have also been studied. 

 While the details of method will appear as the account progresses, 

 it will be well to say that the pressure of the cover-glass may be 

 great enough to vitiate one's Observation. In all cases, therefore, 

 in which this disturbing condition might have obtruded itself, check 

 observations were made without a cover-glass, and whenever single 

 cells were under scrutiny, the cover was supported by a fragment of 

 glass thick enough to prevent pressure or distortion of any kind. 



II. THE NATURE OF THE TANNIN IDIOPLAST 



An adequate idea of the tannin idioplast may be obtained only 

 from the study of living material beginning with the hard unripe 

 fruit. The cutting of a section results in the opening of many 



