The Sporing of the Fern 265 



fulfil all the offices of foliage, while others, which 

 are curiously contracted, produce sporangia and do 

 nothing else. The spore-bearing fronds of the sen- 

 sitive-fern, browned and desiccated by the winter 

 storms, are conspicuous amid the tender greenery 

 of low-lying fields in early spring. The royal 

 Osmunda, called " flowering-fern " also practices 

 division of labor, but practices it less completely, 

 for the lower part of the great frond is green and 

 leaf-like, while the upper portion is a plumy mass 

 of densely-crowded sporangia. 



The development of these sporangia begins in 

 early spring, before the fronds unroll, and they 

 attain their full growth by the first of June. So 

 the royal Osmunda takes more than a month's pre- 

 cedence of less methodical ferns, which make all 

 fronds serve both purposes. 



The sporangium in all the true ferns is formed 

 from a single superficial cell. This cell grows so 

 as to project above the general surface of the 

 frond, and when it is hemispherical it is cut in 

 two by a crosswise partition. 



The inner section will become the stalk of the 

 sporangium, and the rounded outer portion will 

 eventually be fashioned into the sporangium itself. 



But in the adder's-tongues and some other fern-. 



