ON BEPRODUCIION. 373 



Arcliegonia differ considerably in tlieir structure from the 

 AiitUeridia, they consist of bottle-shaped cells into which 

 the spermatozoids have been seen to enter, and are 

 supposed to fertilize the embryo contained in the cells, the 

 result being the production of a young- plant on the upper 

 surface of the prothallium, as above stated. According to 

 vrhat is now explained a prothallium is monoecious, in some 

 cases supposed to be dioecious. The latter having recently 

 been found to be specially the case with the prothallia 

 of OsmundecB. This singular discovery has excited con- 

 siderable interest among physiologists ; and has been care- 

 fully investigated by several, especially in this country, by 

 the late Professor Henfrey, as recorded in " Linnean 

 Transactions," vol. xxi, 1853. Recently considerable 

 attention has been paid to the subject by M. E. Meyer, 

 Inspector of Carlsruhe Botanic Gardens, who in the 

 " Gartenflora " for February, 1875, gives his practical 

 experience regarding raising Ferns from spores. He says 

 he has only succeeded in raising one plant of the genus 

 Oleiclunia, 0. d/icarpa, and one plant of Marattia, M. lati- 

 folia,* and that he has failed in raising UijmenopWiijllece, 

 which he accounts for by the moist nature of the fronds, 

 and the spores bursting in the sporangia soon losing 

 their vitality by becoming dry. 



Much investigation is, however, required before many 

 circumstances attending the germination of spores can be 

 explained, such as, why the Desmobrya division does, as a 

 general rule, increase the abundance of spores, even to 

 some species becoming weeds in the hothouses ; while, on 

 the other hand, those of the division Eremobrya are com- 

 paratively few. 



* This, however, is no rule, for ahout 20 years ago numerous plants 

 of Marattia cicutaifolia were raised from spores at Kew. 



