io Development of the Fern Leaf 



becomes compound later, or whether it is compound from the 

 first. 



The development of the form of the leaf that is simple at 

 first and remains simple, while obviously differing in different 

 species according to the phases through which the leaf passes 

 and the ultimate form to be produced, need not be described 

 here. 



The development of the form of the leaf that is simple at first 

 and becomes compound later, and of the form of the leaf that is 

 compound from the first, can be best understood by ascertaining 

 the various ways in which simple leaves become compound and 

 compound leaves more so. In the following description of the 

 ways in which this occurs in our northeastern ferns, for the sake 

 of brevity, each of the various processes will be described as if 

 continuous and taking place in a single leaf, but the reader will 

 bear in mind that in reality each is exemplified in a series of 

 leaves. 



The student of actual specimens illustrating these processes 

 will find it necessary to bear in mind also that, (i) as the com- 

 plete series of leaves is not likely to be borne by any one plant, 

 and (2) as it could scarcely be considered remarkable if 

 some steps in any one of the processes, although portrayed at 

 first, should in the course of time come to be partly or wholly 

 obliterated, as a rule, in the series borne by the plants of a species, 

 hence, (3) that failure to find some steps portrayed in the series 

 borne by one plant, or even in the series borne by many plants 

 of a species, which often occurs, does not necessarily mean that 

 these steps are not portrayed at the time or have not been por- 

 trayed at some former time in the series borne by any plant of 



