234 The Anatomy of Plants book ii 



came to be added to the results of the anatomists, theories 

 of descent of greater or less probability were sedulously 

 worked out. It cannot be said, however, that at the end 

 of the century the leading problems had even approximated 

 to a solution, though, as we have seen, certain foundations 

 were held by many to have been laid for the construction 

 of a true phylogenetic tree at no very remote period. The 

 theories, however, from whatever source derived, failed to 

 supply a plausible view of the origin of the Angiosperms. 



Of independent work covering the whole field of the 

 recent or existing Pteridophyta, probably the most impor- 

 tant was Bower's Studies in the Morphology of Spore- 

 producing members. This remarkable work extended over 

 the years 1891 to 1903, and contained the record of inves- 

 tigations into the formation, development, and structure of 

 the sporangia of all the groups of the Vascular Cryptogams. 

 It was conceived in support of its writer's views on the 

 sporophyte as an intercalated structure in the life-cycle 

 of the plant, a theory which has been examined in a pre- 

 vious chapter. It claimed to trace, or to render probable, 

 the development of the vegetative system of the sporo- 

 phyte from originally sporogenous tissue, by a system of 

 progressive sterilization, followed by development of the 

 sterilized tissue, so leading to a gradually increasing segre- 

 gation of sporangia. Whatever view may be taken of the 

 author's theory, it cannot be denied that the work con- 

 stituted a wonderful piece of anatomical research and led 

 to more accurate views of the structure of sporangia and 

 their relationships than any other research of the period. 

 It may well claim to be mentioned side by side with the 

 researches of Hofmeister. 



Of very great importance here, as elsewhere, was Goebel's 

 great research on the comparative development of sporangia 

 in 1880 and 1881. 



Another investigation of considerable scope, ranging 



