igii] Francis Ernest Lloyd 29 



perimental evidence is adduced in support of the view that the occur- 

 rence, on the outside of the cell, of granulär matter giving tannin 

 reactions is due to union between dissolved and escaped tannin and 

 pectose or a similar substance on the outside. 



If a few fragments of commercial tannin be mounted for micro- 

 scopic Observation in some clear fruit Juice, the tannin will, after 

 Solution, at once unite with some constituent of the juice to form 

 a granulär precipitate. In water it does not, of course, precipitate 

 but dissolves. The precipitate may be shown to give tannin reac- 

 tions. It is insoluble in water. If a Solution of commercial tannin 

 be added to a Solution of fruit juice in a test-tube, a cloudy precip- 

 itate occurs. 



A strong Solution of commercial tannin was run into a short 

 fragment of a very fine capillary glass tube. This was mounted 

 for microscopic Observation in fruit juice with or without the 

 addition of a weak ferric acetate Solution. At the mouth of the 

 tube a dendritic precipitate was formed. If not already stained, 

 as it was in the ferric acetate Solution of fruit juice, it gave the 

 tannin reaction upon applying appropriate reagents. 



While these experiments prove that a granulär precipitate is 

 formed in the union of tannin and some constituent of fruit juice, 

 the variety of membranes obtained by the exudation of free tannin 

 f rom the cells was not duplicated. This is, I think, because in these 

 experiments, the tannin merely diffuses, while a mass movement is 

 necessary for the production of membranes such as have been 

 described. I have tried to Imitate this condition, but the Operation 

 is so delicate that thus far I have been defeated. 



The insoluble tannin within the tannin-mass. The question 

 of the precise position within the cell of this soluble tannin, which 

 under the internal pressure of the tannin-mass exudes through 

 minute openings of the cell wall, now confronts us. The reader 

 is asked to recall that the tannin-mass lies with its surface juxta- 

 posed to the protoplasm ; that this contains vacuoles proper to it ; 

 and that no evidence may be obtained that tannin dissolved in sap 

 exists between the tannin-mass and the protoplasm. On the 

 other band, it may be shown conclusively that there is no tannin 

 of any kind either in the protoplasm itself or in its vacuoles. Any 



