nated by a special force with speci'al phenomena and special 

 activities, even as in mineral substances there is a special 

 dominant force which produces special phenomena and ex- 

 ercises special activities. 



It is possible to produce crystals in the laboratory, but 

 no one will be so foolish as to maintain that in nature 

 crystals are not formed in consequence of a very definite 

 force inherent in the mineral-substances; nor will any one 

 deny the existence of the force of crystallization because it 

 does not appear in living organisms. 



Nor have I ever despaired of a return of the theory of 

 vital force. A change of opinion has really taken place dur- 

 ing this decade; at present the voices for a vital force are 

 constantly growing stronger and it will most probably not 

 be very long before it will be again universally recognized, 

 not as something preternatural, of course, but as a force 

 of nature on an equal footing with the other forces of 

 nature, with activities, just as mysterious and just as well- 

 attested as the activities of the other forces of nature. 



Haberlandt's experiment, however, had also an in- 

 direct consequence that is of far-reaching importance. He 

 observed that within a few days new water-secreting organs 

 of an entirely different structure and of different origin 

 were formed on the leaves that had been sprinkled with 

 sublimate. Over the bundles of vascular fibres, little knots 

 as large as a pin head arose in larger numbers out of a 

 tissue underlying the top layer; out of these the water now 

 oozed every morning. Closer investigation disclosed the 



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