152 THE NATURE AND ORIGIN OF LIFE 



masses living isolated, endowed with assimilative power, and 

 formed of colloid substances which their state enables them 

 to distribute into two groups nuclear substances in the 

 centre and cytoplasmic substances in the periphery. In 

 every case where their structure is well known, living cells 

 must be considered as formed of two distinct colloid* parts, 

 just as an electric couple in the Voltaic pile contains zinc 

 and copper. 



Perhaps this comparison is nearer the truth than has 

 hitherto been believed. Perhaps there are differences of 

 electric order between the cytoplasmic and the nuclear pro- 

 toplasms. The greater affinity of the nucleus for basic 

 aniline colours might even be taken as a proof of these differ- 

 ences of electric order, if we can trust the interesting work of 

 Jean Perriii on electrification by contact and on the nature 

 of the part played by the substances called mordants in 

 dyeing. 



Such an approximation may be premature. But we find 

 in nearly all vital phenomena a duality analogous to that of 

 the two electricities, as shown in the sexual manifestations 

 so general through the whole extent of biology. 



Meanwhile, this comparison with the electric pile leads 

 us to yet another remark on the dimension of cells. We can 

 make the couples of the pile as large as we wish, with a very 

 considerable surface ; we can also make them very small, 

 and we can leave them isolated or combine them. By a 

 combination in quantity we obtain the equivalent of a single 

 large-surface couple ; by combining their tension we obtain 

 a result which no single couple, no matter how large, could 

 produce. In the same way, we are acquainted with very 

 large cells visible to the naked eye. We are acquainted 

 with very small cells, invisible even under the microscope. 

 We also know beings formed by agglomerations of cells and, 



