PREFACE 



The publication of this book is one of the more harmless consequences of the Second 

 World War. The scientific work which it contains was begun in 1932, at first with no 

 clearly defined programme but rather as a hobby in relation to a field botanist's 

 interest in some attractive British plants, although in part also as a salutary exercise 

 and test of skill. For the Pteridophyta are difficult cytological material. They keep a 

 cytologist on his mettle the whole time to an extent that the student of the more familiar 

 Flowering Plants only rarely experiences, and only by patience, skill and the application 

 of the most modern methods can success be achieved. It is, indeed, no accident that, 

 in spite of three-quarters of a century of 'modern' cytological research by many 

 workers to whom at first the Pteridophyta were familiar and much used material, there 

 is at present practically no single species except Osmunda regalis for which the available 

 published accounts can be accepted as accurate. This much will at once be clear to 

 anyone who takes the trouble to compare the photographs reproduced in this book with 

 the quotations from the literature in even a recent compilation such as that of Love 

 and Love (1948). To remedy this state of affairs individually for each species to be 

 handled has therefore been a problem in itself, and only after the inquiry had been 

 in progress for some years did the several parts of it begin to take on the coherent 

 form of a wider investigation on the lines indicated in the first two chapters. Some 

 of the episodes, notably the study of autopolyploidy in Osmunda (Chapter 3), were at 

 an advanced state of completion fairly early, since in this particular case the inquiry 

 had been used as a preliminary study, on material of known origin and with fairly 

 large chromosomes, to serve as a background to the elucidation of cognate problems 

 in other groups. The published accounts which subsequently appeared, of the flowering 

 plants Biscutella and Nasturtium, undoubtedly benefited greatly by this procedure, 

 though the work on Osmunda itself remained unpublished. Other subjects, notably 

 the taxonomic analysis of the Male Fern (Chapter 4), were undertaken as it were 

 involuntarily, having arisen as an unexpected complication in an inquiry intended 

 to elucidate the cytology of apogamy. This in turn led on to the wider consideration of 

 the British species oi Dryopteris (Chapter 5) and so on. Being incidental to other work, 

 very little had been rounded off for publication before the war broke out and, indeed, 

 the only significant item had been the appearance of a preliminary note on the Male 

 Fern published in Nature in August 1939, in reply to a longer paper by Dopp on the 

 same subject, which had been received in July of that year. Immediate publication of a 

 fuller statement on the Male Fern work would have followed the appearance of the 

 preliminary note, and this would have been succeeded by serial publication of the 

 other subjects but for the outbreak of hostilities in September 1939. The gravity of the 

 international situation then made it appear somewhat frivolous to continue such a 

 programme at such a time, and as a matter of deliberate policy throughout the war 

 years publication was only attempted for work of exceptional importance. As regards 



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