568 Black : The imbedded antheridium in Dryopteris 



antheridia are the result of dryness and not abortive archegonia, 

 may be due to the amount of moisture supplied. In dioecious 

 ferns the archegonia are found on the larger prothallia, the anther- 

 idia on the smaller. Good cultural conditions may favor the prob- 

 ability of a destined sex organ, female ; poor cultural conditions^ 

 male, although experimental evidence is conflicting on this point. 

 While the data are not so complete for ^^ Nephrodiitut moUe^^ 

 as iox Dryopteris stipiilaris, less material of the former having been 

 prepared and studied, the origin of the imbedded antheridium 

 found in this fern is undoubtedly similar to that of Dryopteris 

 stipiilaris. That the structures seen m figures 12— i^ would develop 

 into imbedded antheridia can not be definitely stated, but that 

 deep-seated antheridia could originate in this manner is certain. 



L 



J 



A more exhaustive study of both ferns may bring out more facts. 

 Normal antheridia, imbedded antheridia, and a transitional stage 

 {^figure ii) where an antheridium had a deep-seated origin but in 



■ t 



its development projected beyond the surface of the prothallium^ 

 were all found in " Nephrodhun moiled 



The condition represented m figures 18-2^ is a different expres- 

 sion of " Nephrodium molle " under a dry state. The origin of the 

 structure {c) in figures 22-24., ^^ the base of which are the apparent 

 egg- and ventral canal-cell, is without question a cell which under 

 normal conditions would have given rise to a normal archegonium. 

 The impossibility of this Q.<g^ being fertilized, due to its position 

 and the improbability of a sperm being attracted to it, is obvious. 

 What the other two structures would give rise to is unknown. 

 That they might produce egg-cells is a possibility, or that they 

 might become imbedded antheridia is also to be considered. 



It is impossible to draw any parallel between the imbedded 

 antheridium of these ferns and the antheridium of Ceratopteris, the 

 latter being borne on an aquatic fern, and structurally similar to 

 the ordinary antheridium. 



No apogamous sporophytes were found in the cultures of either 

 fern. In anticipating the production of apogamy in these ferns, a 

 type of sporophyte was expected similar to that described by Lang, 

 i. e., sporophytic budding from the prothallium or upon- a process 

 from the prothallium. If the sporophytes produced from the 

 spore-grown prothallia of Lang do not originate from vegetative 



