L56 



THE AMERICAN NATURALIST [Vol. XLII 



number of plants, mostly phanerogams, but also a num- 

 ber of liverworts and pteridopliytes. His researches 

 showed the presence of an endophytic mycorhiza in a 

 surprisingly large number of plants belonging to the most 

 diverse families, from Zoopsis, one of the Hepaticae, to 

 Vernonia, a genus of Composite. 



The study of the mycorhizal fungi of the seed plants 

 has called attention to the presence of similar fungi in 

 the pteridophytes. The occurrence of a mycorhiza in the 

 roots of the Ophioglossacoa 1 was first shown by Russow. 3 

 In 1884 Treub described a similar fungus from the game- 

 tophyte of Lycopodium. In his very important paper 

 on the prothallia of Lycopodium 4 he pointed out the 

 universal occurrence of this fungus in L. cernuum, and 

 in later papers lie showed that this also occurred in L. 

 phlegmaria, as well as in some other species, but it was 

 apparently absent from the green prothallium of L. sala- 

 kense. In 1895 I called attention to the presence of a 

 similar endophytic fungus in the subterranean prothal- 

 lium of Botrychium virginianum. 



The past decade has been notable for the numerous 

 important investigations upon the gametophytes of the 

 Ophioglossacea^ and the Lycopodiaceae and our knowl- 

 edge of these is now quite complete, thanks to the labors 

 of Bruchmann, Lang and Jeffrey. It is clear that in all 

 prothallia of the subterranean, and hence purely sapro- 

 phytic type, an endophytic fungus is invariably present. 

 It has also been shown that a similar form occurs in the 

 green prothallium of some species, at least, of Lycopo- 

 dium ; but so far as I am aware its occurrence in the green 

 prothallium of ferns has not hitherto been recorded. 



Some time ago, having occasion to look over slides of 

 the prothallium and embryo of Osmunda cinnamomea, it 

 was noted that many of the prothallia contained an endo- 

 phytic fungus very similar to that found in Botrychium 



* Vergleichende Untersuchungen dor Leitbiindelkryptogamen. Mem. de 

 V Alcoa. Imp. aes Sc. de Petersbourg, 1872, XIX, 107-118. 



1 Etudes sur les Lycopodiacees. Ann. du Jardin Botanique de Buiten- 

 zorg, IV, 1884. 



