362 SCIEXCE PROGRESS. 



This has the property of causing the soluble pectic bodies to 

 gelatinise. Recently Bertrand and Mallevre (23) have again 

 investigated the action of this ferment pectase, and have dis- 

 covered that its action is not to cause the formation of 

 pectic acid as Fremy supposed, but a pectate of calcium. 

 By careful experiments they have shown that if Fremy's 

 mode of preparation of pectine be followed, and then the 

 pectine be carefully washed with a mixture of alcohol and 

 hydrochloric acid till all traces of calcium are removed, 

 a solution of such pectine will not clot on the addition of 

 pectase which is also free from lime salts. If a small 

 quantity of calcic chloride be now added, clotting takes place 

 gradually, the length of time required being proportional to 

 the quantity of the calcium salt used. The formation of 

 calcic pectate which can thus be induced outside the plant 

 by ordinary laboratory methods may well represent what 

 goes on in the plant itself. It is well known that in the case 

 of many of the unorganised ferments the enzyme carries out 

 a process which can quite easily be effected by the pro- 

 toplasm alone. If we have as Wiesner suggests a kind of 

 framework of protoplasm throughout the whole of the un- 

 altered cell-membrane, and we have slowly passing into or 

 through the wall, under the influence of the internal osmotic 

 pressure, a stream containing soluble pectates, and the usual 

 mineral bodies of the cell sap, in which calcium salts must 

 always be included, there seems no difficulty in explaining 

 the deposition of calcic pectate in the form of a definite 

 lamina where the pressures from two contiguous cells oppose 

 each other. 



Mangin in his paper rather holds to the other view, 

 judging from experiments in rupturing the young cell- 

 membranes, that there is first formed a layer of pectates, 

 that indeed the first microsomata that are accumulated across 

 the cell spindle have this composition. 



The formation of intercellular spaces probably depends 

 upon the behaviour of the calcic pectate. During the 

 period of cell division the cells contain only protoplasm with 

 a little water and there is little internal pressure. The cells 

 are in close contact with each other and polyhedral or 



I 



