202 SIGNIFICANCE OF MALFORMATIONS IN ORGANOGRAPHY 



to deal with an increase in the quantity of the material for forming 

 flower-leaves. This expresses itself sometimes in a splitting of the normal 

 primordia of the flower-leaves, sometimes in the appearance of new 

 primordia of flower-leaves, sometimes in the transformation of the prim- 

 ordia of other leaves of the flower to petals with which are associated 

 frequently profound disturbances in the construction of the primordium 

 of the whole flower. 



In 1887 Sachs explained 1 that he did not include in his concep- 

 tion of the ' flower-forming material ' the whole mass of material out of 

 which a perfect flower or flower-bud arises. ' What I understand is that 

 extremely small quantities of one or of different substances (chemical 

 combinations) arise in the leaves, and these then so influence the plastic 

 materials which as we know flow into the vegetative points that they 

 assume the form of flowers. These flower-forming materials may act 

 like ferments upon a large mass of plastic substance whilst their own 

 amount is extremely small.' This conception conforms entirely with 

 the views upon transformation to which we have been led above. It 

 rests further upon the ground of ' epigenesis ' ; just as the configuration 

 of a starch-grain is conditioned by the material nature of the starch- 

 producing plant, so also is the form of organs affected by the plastic 

 material for their construction. 



Beyerinck 2 also, as a result of his studies of the formation of galls, 

 was led to the same conclusion as Sachs. He assumed that the gall- 

 forming material excreted by insects has the character of an enzyme, 

 1 groivth-enzynie ' he called it, which so influences the protoplasm of the 

 host-plant that the formation of a gall ensues. Following the lead of Sachs 

 he also assumed that such 'growth-enzymes' are present and active in 

 the normal formation of organs, only in this case they are formed by the 

 protoplasm of the plant itself. As these enzymes must obviously be 

 different for different organs, Beyerinck's view conforms with that of 

 Sachs. 



This short reference to these general questions must suffice here. 

 In this difficult field we can only as yet deal with similitudes; we are 

 unable to treat in detail complete theories. Every general interpreta- 

 tion however will be the more fruitful the more it makes possible a clear 

 issue for further experimental investigation. 



1 Sachs, Gesammelte Abhandlungen iiber Pflanzenphysiologie, i. p. 307. 

 3 Beyerinck, in Botan. Zeitung, 1888. 



