INDUCED APOGAMY 



than a merely confirmatory usefulness. It is a well-known fact that in many genuine 

 haploids a limited power of pairing may be conferred on essentially non-homologous 

 chromosomes by small structural lesions such as reduplications or translocations of re- 

 duplicated segments. These structural changes within chromosomes may, or may not, 

 alter the genetical content of the nucleus as a whole, and they may or may not be 

 detectable in the external morphology of the plants. The evolutionary importance of 

 structural changes within the monoploid set is, however, far greater than their imme- 

 diate visible effects might suggest. They introduce changes of behaviour of a wholly 



X 





;$♦»' ^tr ^ 



V 





a 

 Scolopendrium n - 36 



Fig. 2IO. Explanatory diagram to Fig. 209 a and b. x 1500. 



different type from those so far studied in the Pteridophyta, and any practicable means 

 for bringing them effectively under observation is much to be desired. 



So much is this the case that it may be suggested that one of the most fruitful lines of 

 inquiry at present outstanding in the cytology of the British fern flora is the extension of 

 induced apogamy to other wild species besides Scolopendrium. That this might not be im- 

 possible is suggested by the relatively large number of species represented on Lang's 

 original list, and if it could be done on any scale, more insight might in a short time be 

 gained about the cytogenetic composition of our native species than would be expected 

 to be reached in any other way. It is therefore much to be hoped that this work will be 

 extended. 



SUMMARY 



The induction of apogamy in two well-known horticultural strains of Doodia caudata 

 (Cav.) R.Br, (the strain used by Duncan, 1941) and Scolopendrium vulgare (the strain used 

 by Lang, 1929) has been repeated by methods previously described by earher workers 

 with the object of including cytological observations on them. In both cases the apo- 

 gamously produced plants were raised to reproductive maturity and meiosis seen. In 



207 



