THREE SPECIAL CASES OF FERN HYBRIDS: 



151 represent meiosis in which the number is quite certainly n = 36. S. hemionitis, Hke 

 S. vulgare, is therefore a diploid species, and both contrast equally strongly with S. hybridum. 



At this point it is greatly to be regretted 

 that the programme of experimental work 

 planned for this species but interrupted by 

 the war has not yet been resumed. The 



L«l^ 





a b 



Fig- 1 50- Chromosomes of Scolopendrium hemionitis Lag. , 

 Garcia & Clem., from sections, x 1000. a. Meiosis. 

 n = 36. For explanatory diagram see Fig. 151. 

 b. Mitosis in a root. 2n='j2. For comparison with 

 S. hybridum see Fig. 148 a. 





S hemlonlNs n^36 



Fig. 151. Explanatory diagram to 

 Fig. 150 a. X 1500. 



origin of S. hybridum is therefore still un- 

 certain, and, with the experience of Dryopteris 

 remota and Asplenium germanicum in our minds 

 it would be unwise to predict a conclusion 

 before the evidence is fully assembled. We 

 have three suggested parents to consider. 

 The two species of Scolopendrium are both suit- 

 able in chromosome number, but whether 

 either is actually related can only be deter- 

 mined by crossing S. hybridum with each and 

 examining chromosome pairing in the tri- 

 ploids so obtained. There remains, however, 



Fig. 149. Scolopendrium hemionitis Lag., Garcia & Clem. 

 Living leaf of the same plant as Fig. 147^, grown in 

 cultivation showing characteristic auricles. Natural 

 size. For description see text. 



146 



