KAINEY, ON STARCH GRANULES. 9 



noticed, more decided in the latter than in the former. 

 Now, gum is not the produce of any particular vegetable 

 cells, nor is it confined to any class of plants, but it appears 

 to be a secretion generally diffused through the tissues of all 

 plants. Hence, combining these two circumstances, the 

 general existence of gum in vegetables, and its property as a 

 precipitant, I hold that one of the conditions necessary for 

 explaining the presence of solid substances in the cells of 

 plants by a process of precipitation is demonstrated. I need 

 scarcely add, that the solution of gum would gain access to the 

 fluid within the starch-cells — allbyaprocessofendosmose. And, 

 as to dextrine, it is generally admitted to be matter assimi- 

 lated in the cells of plants for the purposes of nutrition, and 

 therefore it is only necessary to suppose that in certain cells 

 some such a solution of starch, as that made artificially 

 by mixing starch and alkali together, is elaborated; (and 

 alkali, in some form or other, is well known to be essential 

 to the growth of plants,) and then we shall have the other 

 condition requisite for the same process. And with such 

 conditions there is no difficulty in seeing how a kind of mo- 

 dified starch, as cellulose, or the imperfect forms of chloro- 

 phyll e, would be deposited in the former cells, those con- 

 taining the dextrine, and pure starch in the latter. I 

 am perfectly aware that this explanation will be considered 

 by the vitalists as being too physical, but still it is no more 

 so than the formation of bodies of a similar form in the shells 

 of Molluscs and Crustaceans. The molecules of starch being 

 thus formed and deposited, will, after repeated coalescences, 

 produce all the forms described and represented in the 

 accompanying plate. 



The form of some of the larger starch granules may appear 

 at first sight to have no representatives among the calcareous 

 deposits, either natural or artificial, but this is perfectly ex- 

 plicable upon physical principles, and, when duly considered, 

 is in favour of the principle of molecular coalescence. A 

 similar difference of shape, though not to so great an extent, 

 obtains also with the natural and artificial globules. In all 

 the three cases the most nearly spherical forms of single 

 globules are among the smallest, the mutual attraction of 

 their molecules upon which rotundity depends, being less in- 

 terfered with in these by the simultaneous attraction of sur- 

 rounding objects than in the larger globules, as would be 

 the case with globules of quicksilver of different sizes, placed 

 upon a piece of glass or a sheet of paper, the smallest would 

 be the roundest. As the particles get larger their molecules 

 become more effectively attracted by adjacent masses of 



