35 



intercalation of new particles. But this is not all that has been 

 determined with regard to these micellae, for in 1862 a paper 

 appeared by Nageli,* in which were contained these results. He 

 found, in the first place, that organized structures, such as starch 

 grains and cell-walls, are doubly refractive under the polariscope ; 

 and further, that this property is not affected by causing them 

 either to increase or to diminish in size either in consequence 

 of absorption or removal of water, or by mechanical stretching 

 or pressure. It is well known that double refraction is a pro- 

 perty characteristic of some crystals, and hence it might be 

 supposed at first by some, that the cell- wall was simply a 

 crystallization outside the protoplasm ; but if this were so we 

 could interfere with its optical properties just as we can do with 

 the optical properties of crystals, for these last, when treated 

 with reagents, swell up, and their double refraction either 

 disappears or is changed in a marked degree ; but, as we have 

 just stated, Nageli found the reverse to be the case with regard 

 to the micellae. He concluded, therefore, that the double 

 refraction is not a property of the organized structure as a 

 whole, but that it belongs to each individual micella; and 

 hence these micellae must be crystalline. Again, from the 

 interference colors which these objects present when examined 

 with polarized light, he ascertained that the crystalline micellae 

 have three axes of elasticity, that they must be biaxial crystals ; 

 and further, by comparing the effect produced by the passage 

 of polarized light through glass under various degrees of 

 pressure, he arrived at the conclusion that the micellae are so 

 arranged in the membrane of which they form part, that one of 

 their axes of elasticity is perpendicular to the surface, while 

 the other two axes lie in the plane of the membrane. Nageli 

 has also shown that the crystals of proteid substance which 

 occur in various seeds and tubers have the same molecular 

 constitution as starch grains and cell-walls. The outcome of 

 this theory in relation to the movement of fluid in the wood 

 will be seen hereafter. At present we will only pause to notice 

 in how far it is applicable to the protoplasm. There can be 



* Proceedings of Bavarian Academy, i86z, 



