622 . Graham : Conocephalum conicum 



should not be confused with the pseudoperlanth such as appears 

 in certain other Marchantiaceae, e. g., in Marchantia and Preissia. 

 That structure originates as a collar-like outgrowth from the cells 

 immediately beneath the base of the archegonium, which are de- 

 scendants from the original cell from which the mother-cell of the 

 archegonium was cut off. Only the slightest indication of this 

 organ appears at the time of fertilization, so that it is an entirely 

 new structure which develops after fertilization has taken place. 

 At its maturity it is a tubular sheath, a single layer of cells in 

 thickness and is never closed or continuous around the distal end 

 of the sporogonium. Such a true pseudoperianth does not exist 

 in Conocephalum conicum. It is replaced by the sheath which 

 has already been described as being a further development of the 

 walls of the cavity in which the archegonium is developed. It is 

 composed of several distinct laminae, which are morphologically 

 the plates of cells separating the air-chambers on one side of the 

 archegonial cavity and at maturity completely enclosing the 

 sporogonium and calyptra. 



The function of this enveloping sheath may possibly be pro- 

 tective. Since the sporogonium rests over winter in the nearly 

 mature condition, this extra covering, with its air spaces, may 

 serve to prevent excessive radiation and transpiration. 



Department of Botany, 

 Cornell University, 

 Ithaca, New York. 



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