CHAP, in The Study of the Cryptogams 237 



the development of the prothallia of the Gleicheniaceae in 

 1879 and further in 1890. In the latter year Poirault 

 investigated the structure of the stems of various species 

 of this group. 



Prantl wrote an account of the structure of the sporangia 

 of the Schizaeaceae in 1881, based upon his own researches. 

 Several years earlier, in 1875, he gave a complete descrip- 

 tion of the structure of the mature sporophyte of Hymeno- 

 phyllum, whose antheridia were investigated by Goebel in 

 1888, together with those of Trichomanes. Bower studied 

 the latter in the same year, and investigated the meristems 

 and resulting structure of the sporophytes of the whole 

 sub-group in 1889. 



The Hydropterideae, or, as they were formerly called, 

 the Rhizocarpeae, attracted much attention. The earliest 

 work of our period was the classical work of Pringsheim 

 on Salvinia in 1862, which was an excellent research. In 

 earlier years Hofmeister had studied the germination of 

 the spores and traced out many important points about 

 the female prothallium. Juranyi worked out the processes 

 of development of the sporangia and spores in 1873, and 

 Prantl reinvestigated the formation of the prothallia in 

 1879. Archangeli also contributed a memoir dealing with 

 Salvinia and Pilularia in 1876. 



The structure of the mature sporophyte of Azolla was 

 worked out by Strasburger in 1873. This research was as 

 thorough and complete as was that of Pringsheim for 

 Salvinia, and stands now as the basis of our knowledge. 

 In 1881 its prothallia were investigated by Berggren and 

 found to correspond in all essential particulars with those 

 of Salvinia. Belajeff traced out the development of the 

 microspores in 1892 and in the next year Campbell investi- 

 gated the development of the prothallia. Our knowledge 

 of Marsilia is largely due to the researches of Hanstein, 

 carried out in 1862 and 1865. In a third memoir in 1866 



