238 The Anatomy of Plants BOOK n 



he made a careful comparison between this genus and 

 Pilularia. Russow also studied Marsilia in 1871. In 1898 

 the development of its leaves and sporocarps were the 

 objects of a research by Johnson. 



Besides the researches on Pilularia, incidentally alluded 

 to, mention should be made of Braun's work on the genera 

 Pilularia and Marsilia of 1870, and of Campbell's work 

 on the development of the gametophytes of the former, 

 carried out in 1888. 



Descriptions of various features of the anatomy of these 

 plants were given also by Naegeli and Leitgeb in 1866 and 

 1867, and by Millardet in 1869. The latter was chiefly 

 concerned with the structure of the male prothallia of the 

 whole group of the Pteridophyta. 



Hardly second to the Filices in interest as the subjects 

 of research were the Lycopodinae. As in the former case, 

 many works based upon comparative study of the whole 

 group appeared from time to time, while researches upon 

 the several genera and species were numerous. The ana- 

 tomy of the sporangia forms part of the papers by Goebel 

 and the studies by Bower, which have already been alluded 

 to. The roots were investigated by Naegeli and Leitgeb 

 in 1867, and the male prothallia by Millardet in 1869. 



The anatomy of Lycopodium was the subject of researches 

 by Hegelmaier in 1872 and 1874, which were chiefly con- 

 cerned with the vegetative parts. The anatomy of the 

 stem and the constitution of its tissue-elements were more 

 completely investigated by Strasburger in 1888-93, while 

 a comprehensive discussion of the structure in the whole 

 group was contributed by Jones in 1898. Bruchmann 

 investigated the roots in 1874. The development of the 

 sporangia was treated of by Goebel and by Bower, as 

 already mentioned. The development and structure of the 

 gametophyte in various species were studied by several 

 botanists. The germination of the spores was first observed 



