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teristics already possessed by collateral forms, he has been 

 brought face to face with the elemental fact upon which any 

 real understanding of evolution must be based. His clear per- 

 ception of this primary fact will enable him to analyze and ap- 



Photograph from the Brooklyn Garden 



Figure 1. Vegetative reproduction in Nephrolepis. In this case, the three 

 bud plants are all like the parent. In variation one or more would be different. 

 Such a variation would have to take place along the slender connecting stem. 



predate the meaning of the whole problem. He will be looking 

 at the problem sharply and clearly, not merely vaguely and in 

 the large. The methods of the proposed lesson are outlined in 

 detail as follows : 



