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The S^porangia are of a considerable size in pro- 

 portion to the leaf, and are borne on short, thick 

 stalks. Each fertile leaf bears a single sporangium, 

 which always lies below the ligule, either on the 

 leaf itself or on the stem. Each sporangium is a 

 capsule. 



Capsules containing four (2-8) large spores 

 (female) are called rnegasporangia or macrosporangia. 



Capsules containing an indefinite number of small 

 spores (male) are called microsporangia. The micro- 

 sporangia are borne on one side of the branch, and 

 the megasporangia on the other aide, or the micro- 

 sporangia above and the megasporangia below. 



DEVELOPMENT. 

 The early stages are the same in both cases. 



I. Microsporangia. 



(1) A group of superficial cells in the axil of the 

 Hgule becomes active, and gives rise to a small 

 protuberance. By repeated division a mass of 

 tissue is formed which differentiates into an 

 outer layer and an internal group, one of which, 

 the hypodermal cell in the axial row, becomes 

 the archesporiutn, and the lower ones the stalk. 



(2) The archesporium cuts off cells which go to 

 form the tapetum on the free side, and the cells 

 of the ground tissue form it towards the base. 



(3) After the development of the tapetum, the 

 archesporium divides up rapidly, and produces 



