-2- 



molecules also show an unequal density, since the greater 

 dipmeter corresponds to the less dense envelope. This is a 

 cause for the molecules at the poles now developing a greater 

 rfass than at the lateral surfaces, and this theoi-y also agrees 

 with the facts already given that there is less water lodged 

 between the molecules in the radial than in the tangential 

 direction. In the transverse (tangential) section of the 

 molecule, the interstices have-a between tlie 3 or 4 molecules 

 which lie beside one another are triangibDiar or quadrangular. 

 Mow only these sides of the molecule and the angles which are 

 turned towards the interstices have a chance of having 

 particles from the solution deposited upon them with consider- 

 able force and thus growing by the deposit of material. The 

 transverse section of the molecule has become angular, with 

 the angles turned towards the interstices, which have become 

 narrowed. This alteration from the circular cross-section under 

 similar conditions continues and even increases. 



As the molecule grows, even if the form were 

 originally spherical, it becomes elongated, polyhedral, or 

 prism.atic. The peculiarity of form depnds upon the position of 

 the molecule In reibtion to ohher molecules; thus the outer 

 and inner sides, if turned towards another molecule, become 

 flattened and pointed if directed towards the interstices, •'■he 

 larger molecule, bfreeme-flefefeeHed-sHd-peiRte^-if-f^ir'eefee^ 

 grows the greater the deviation from the original form, both 

 because the movement of the fluid encourages the deposition 

 of new material at the sides turned towards the interstices 

 and because here the resistance to the water envelopes Is 

 diminished. 



Nageli gives in line drawings schematic represent- 

 ations of the form and arrangement of the molecules. In one 

 is shown a hypothetical section of a superficial molecular 

 layer showing among developed molecules or micellae young and 

 as yet spherical molecules, and the molecules with their envel- 

 opes and interstitial canals shown in a tangential direction. 

 In the second figure he represents a part of a hypothetical 

 radial section showing the molecules lying beside one another 

 in horizontal rows belonging to the same molecular layer. 



The structural likeness of the starch-grain to 

 spherocrystals of inorganic substances was first strikinrly 

 pointed out by Faraintzin, who found starch-like forms of 

 crystals of calcium carbonate. He records the parallelisms in 

 the manner of growth, in the lamellation, in the differences 

 in solubility of the inner and outer parts, and in the formation 

 of comnomnd grains and crystals. Erosion phenomena which 

 bear a striking resemblance to those occurring in starch-grains 

 have been observed by Goldschmldt in p spherocrystals of calcivim 

 carbonate. 



