10 RAINKY, ON STARCH GRANULES. 



matter, and thus the centre of attraction common to the 

 molecules of the globule in progress of formation, and the 

 surrounding particles of matter, towards -which centre all 

 these molecules are effectively or ineffectively attracted, 

 cannot be the geometrical centre of the globule in question ; 

 and hence a globule formed under such circumstances cannot 

 be accurately spherical. These conditions must always exist 

 as well during the formation of the calcareous globules as 

 during that of the granules of starch, but they will operate 

 more as disturbing causes in the latter than in the former, 

 just in proportion as the molecules of starch are less dense 

 than those of carbonate of lime. Hence these peculiarities 

 in the form of the large granules of starch are no more than 

 might have been expected. The small granules of starch are, 

 to all appearance, as spherical as those of the carbonate of 

 lime of the same size. For an explanation of the manner in 

 which the granules of starch acquire their laminated form, 

 and the mode in which the hilum, the part corresponding to 

 the central spot in the artificial calculi, is formed, I must 

 refer to my work on the f Mode of Formation of Shells of 

 Animals, of Bone, and of several other Structures, by a pro- 

 cess of Molecular Coalescence/ 



I should have been glad to have introduced into this paper 

 a condensed account of this process, as given in the volume 

 referred to, had not the necessarily elementary character in 

 which the process is there explained rendered the necessary 

 abridgement of that explanation impracticable. 



With respect to the chemical action of gum, and the 

 chemical nature of the deposits thrown from the vegetable 

 juices, I have not yet been able to make any strict investiga- 

 tion. I feel certain, from what I have noticed, that the sub- 

 ject is one of importance, and it is not impossible that it 

 may pave the way to the discovery of similar facts connected 

 with the action of the fluids in animal tissues. In reference 

 to the action of gum in precipitating starch, it is not im- 

 probable that, as starch contains a minute portion of phos- 

 phate of lime, which can only have been derived from the gum, 

 in which this salt is well known to exist, gum may furnish 

 other constituents of starch, and also sonic portion of all the 

 other substances which it has the power of precipitating, and 

 that thus it may act both as a medium by which the various 

 substances existing in plants are carried to the cells in 

 which they are elaborated, and as a means of solidifying them 

 after they have undergone the neccssarv elaboration. 



