MANTON: PTERIDOLOGY 303 



into a previously simpler sexual life history, as an essential part of tlie trans- 

 migration to the land, illustrates, among other things, the radical change in 

 general outlook which the idea of evolution introduced into the interpretation 

 of Hofmeister's facts. It also gives an indication of the nature of one of the 

 stimuli towards intensive fact-gathering which characterized the late nineteenth 

 and early twentieth century. 



One of the greatest lacunae in The Higher Cryptogamia itself is due to 

 the fact that certain groups eluded description. In particular the homosporous 

 lycopods and other genera with subterranean prothalli took nearly the whole 

 following century to elucidate and in some respects our knowledge is still in- 

 complete. The reason is that their spores do not germinate readily, if at all, 

 in cultivation and prothalli in nature are infrequent and difficult to find. A 

 history of their discovery is summarized in the introduction to Bruchmann 

 (1898). Spores of Lycopodium mdundatum had been induced to germinate by 

 De Bary in 1858 but they only developed through a few cell divisions and adult 

 prothalli attached to young plants were only found in this species for the first 

 time by Goebel (1887). In the meantime Fankhauser (1873) had found young 

 plants of L. davatum attached to prothalli and one of these is illustrated in the 

 second English edition of Sachs's textbook (1882). A fuller account of the Euro- 

 pean species is, however, the work of Bruchmann himself. His classic volume of 

 1898 contains descriptions, beautifully illustrated with pencil drawings, of ga- 

 metophytes and numerous developmental stages for L. davatum, L. annotinum, 

 L. complanatum , L. selago and L. inundatum (i.e., all the European species). 

 An extension to the tropics with, in particular, the description of the important 

 prothallial types found in L. cermium and L. phJegmaria, was carried out in 

 Java by Treub (1884-1889). The relevance of these for an understanding of 

 lycopods in general was pointed out by Lang (1899) in a paper describing 

 prothalli and young plants of L. davatum discovered in Scotland and was dis- 

 cussed again, and very helpfully, by Holloway in a series of papers (1915-1920) 

 describing comparable stages for species of Lycopodium in New Zealand. Spore 

 germination leading to mature prothalli was first achieved by Bruchmann in 

 1910 and this paper is still the most authoritative work on the subject. 



With regard to other saprophytic types there is a very beautifully illus- 

 trated account of Ophioglossum vulgatum by Bruchmann in 1904 and some other 

 observations can be obtained from Campbell (1911, 1918) and Manton (1950). 

 Helminthostadiys, the last remaining genus of Ophioglossaceae was described 

 by Lang in 1902. 



The most difficult to elucidate of all the saprophytic gametophytes have 

 proved to be those of the Psilotales. Prothalli were not found for either Psilotum 

 or Tmesipteris until the twentieth century and in both cases our knowledge 

 rests principally on the work of Holloway in New Zealand. A brief history 

 will be found in Holloway (1939). It begins in 1917 with a description of adult 

 gametophytes and some young plants of Tmesipteris in Australia by Lawson. A 

 fuller account of prothalli and young embryos of Tmesipteris in New Zealand 

 came from Holloway himself in 1918 and descriptions of the embryo and spore- 

 ling followed in 1921. One of the more important conclusions, which is clearly 

 expressed even in the 1918 paper, is to emphasize the primitive nature of the 

 rootless habit of Tmesipteris and the apparently primitive character of its em- 



