THE MALE FERN DRYOPTERIS FILIX-MAS 



meiosis can be a very valuable guide to the genetical make-up of a plant. In this 

 way the only condition under which D. abbreviata and D. Filix-mas could not legiti- 



Fig. 35. Acetocarmine squash of Dryopteris Filix-mas sens. strict, 

 emend, showing 82 pairs of chromosomes. For explanatory 

 diagram see Fig. 30. x 1000. 





s 



4 



*7^ 



Fig. 36. Acetocarmine squash of 

 Dryopteris abbreviata Newm. 

 showing 41 pairs of chromo- 

 somes. For explanatory dia- 

 gram see Fig. 31. x 1000. 



Fig. 37. Triploid hybrid between Dryopteris Filix-mas and D. abbreviata. Acetocarmine squash showing 

 40 univalents, 40 pairs and a trivalent. x 1500. For explanatory diagram see Fig. 38. 



mately be separated taxonomically would be if it could be shown that one was 

 merely an autotetraploid form of the other. In that case, however, one would expect 

 to have found quadrivalent groups in B. Filix-mas, but these are certainly absent. 



52 



