146 



pimncipi.es of plant-teratology. 



of this kind naturally give rise to such pseudo-transi- 

 tional organs as Lang describes. The phenomenon of 

 adventitious buds on the fern-prothallus is seemingly 

 comparable to that of similar buds on the Begonia- or 

 fern-leaf and does not in any sense imply a homology 

 between the shoot and the leaf or thallus bearing it ; 

 the same germ-plasm exists throughout the whole 

 plant in both its generations. 



The present mode of alternation between the two 

 generations is clearly antithetic, for the simple and 

 only reason that for the production of the sporogonium 

 or fern-plant, etc., from the oospore, a totally new 

 method of growth of tissue and organ-formation is 

 inaugurated. Why should not the present antithetic 

 method of sporophyte-development have always pre- 

 vailed ? Why try and devise a new, unheard-of 

 method, based entirely on abnormal and exceptional 

 phenomena ? 



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