190 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



The most resistant of seeds, however, cannot have the 

 percentage of water which they contain reduced to lower 

 than between 2 and 3 p.c. of their dry weight without 

 their vitality being affected. It is possible that this 

 water forms an integral part of the dried stable proto- 

 plasmic molecule and in this connection it is interesting 

 to notice that Loew's* equations for the production of 

 proteid by the polymerization of aspartic aldehyde and 

 addition of hydrogen and sulphur give as the final result 

 an albumen having the formula 



C 72 H 112 N 1S S0 22 + 2 H 2 0, or C 72 H 112 N 18 S0 22 2 H 2 0, 

 and containing 2*2 p.c. of water. It appears possible 

 that this or some analogous empirical formula may 

 represent the chemical composition of protoplasm when 

 in the dried condition. A seed is resistant to dessication 

 when its protoplasm can assume and maintain this 

 particular composition for long periods of time. It is 

 interesting to notice that no cell the protoplasm of which 

 shows streaming or rotation can withstand dessication. 

 It appears that where the vital activity of the plasma 

 manifests itself in the form of rotation or circulation, the 

 preservation of vitality is indissolubly connected with the 

 presence of free fluid water in the protoplasm. 



Oxytropic Irritability of Boots. 



In the previous paper an account was given of certain 

 experiments which seemed to lead to the conclusion that 

 the root apices of plants possess a special oxytropic 

 irritability enabling them to seek out the regions in which 

 oxygen is most abundant and avoid those in which it is 

 deficient or absent. Satisfactory demonstration of the 

 pres'ence of such an irritability must always, owing to the 



* Loew. Die Chemische Kraftquelle in lebenden Protoplasma. Miin- 

 chen, 1882. 



