THK VITAL PROPERTIES OF THE CELL 153 



protoplasm, which grows and develops itself at the expense of 

 the substances which it absorbs. Then, from the splitting up 

 of this most complex of all organised bodies, all the complicated 

 ternary and quaternary compounds must arise, the formation of 

 these being ordinarily ascribed to a direct synthesis. Hence 

 Sachs was obliged to allow that it was possible, although he con- 

 sidered it improbable, that in the assimilation of starch decompo- 

 sition and restitution occur in the molecules of the green proto- 

 plasm." 



These remarks show how difficult the whole subject is in so 

 far as it concerns the chemical processes in question. 



If it is allowable to draw conclusions from analogous cases, I 

 must certainly decide in favour of the second hypothesis, accord- 

 ing to which the protoplasm participates more indirectly than in 

 the first in the formation of the greater number of intercellular 

 substances. For in the cases where organisms construct a sili- 

 cious or calcareous membrane the nature of the substance itself 

 distinctly shows that it could not proceed directly as a firm 

 organised substance out of protoplasm. This latter in such a 

 case, in consequence of its chemical composition, can only play 

 the part of an intermediary, by selecting the substances from its 

 environment, absorbing them, accumulating them at the places 

 where they are required, and depositing them in a distinct form 

 as firm compounds, which are invariably joined to an organic 

 substratum. 



Such a conception appears to me to be nearer the truth in the 

 case of the formation of the cellulose membrane also, if the facility 

 with which various carbo-hydrates become transformed into one 

 another is taken into account, as well as the complicated process, 

 which would be necessary if protoplasm were to be converted into 

 cellulose. And even those intercellular substances which are 

 chemically more nearly related to protoplasm, such as chondrin, 

 gluten, etc., may be governed by the same laws of construction. 

 For, apart from the organised proteid substances, protoplasm and 

 nuclear substance, there are always present in each cell a large 

 number of unorganised proteids ; these serve as formative 

 material, and occur in a condition of solution in the cell sap of 

 plant cells, in the nuclear sap, and in the blood and lymph of 

 animals. Instead of the protoplasm itself being directly seized 

 npon and used up in the formation of nitrogenous intercellular 

 substances, it is possible that the unorganised proteid materials 



