202 SECTIONAL ADDRESSES. 



a lighter-green colour, on the clay a more yellowish-green colour, and on 

 the chalky clay a more blue-green colour than in the parent. Secondary 

 growth has occurred especially on the sand. General tone was best on 

 the clay and worst on the calcareous sand. 



In Silene maritima there was a marked though irregular tendency for 

 the plants on the sand to change to plants with smaller leaves, and with 

 more anthocyanin and a flatter habit than in the parent. On the 

 calcareous sand the leaves were narrower and smaller, the plants were 

 flattened, and the calyces more red than in tJie parent. On both clays 

 there was little change from the parent. General tone was best on the 

 chalky clay and worst on the clay. 



To sum up : Ceniaurea nemoralis does not at present appear to be 

 plastic, but will survive under a wide range of edaphic conditions ; Silene 

 vulgaris is slowly plastic under certain edaphic conditions ; S. maritima 

 is decidedly more plastic than its congener ; Anihyllis vulneraria is not 

 plastic, and is not capable of survival under a wide range of edaphic 

 conditions, and Plantago major is exceedingly plastic* 



It is obvious that the experiments, to be of real value, must be con- 

 tinued for a long period of years. The making of soils from raw materials 

 can be slowly followed in the beds, and it is hoped that periodic analyses 

 will yield useful pedological data. 



In Centaurea, Silene vulgaris, S. maritima and Antliyllis genetical 

 research is being continued which involves the use of lines from which 

 the transplant materials originated, and this work is being correlated with 

 field, laboratory and herbarium studies. 



Apart from actual changes in the plants and from stages in soil-making, 

 many interesting biological facts are noticeable. Since the plants are 

 grown in the absence of competition, mass or individual differences must, 

 on the whole, be due to edaphic factors. Plants, however, are individuals, 

 and the history of a given individual is never exactly like that of any 

 other. ' Accidents ' also happen to individuals, and therefore records 

 must as a rule be of a statistical nature with the limitations of this method. 



Though the Kew-Potterne transplant experiments may be regarded as 

 being only in their infancy, it is already evident that the experiments 

 are yielding information of great value in the domains of Taxonomy, 

 Ecology and Genetics. These results are of all the more value owing to 

 the careful records which are being kept for each individual plant, whose 

 history can be traced from the commencement, and may also be studied 

 in the extensive series of herbarium specimens which are being preserved 

 at Kew. 



In addition to what the Taxonomist is seeking to discover from this 

 intensive study of plants by means of ' transplant experiments,' he is also 

 anxious to elucidate the problems associated vnth. certain ' critical ' British 

 and European genera, such as Silene, Centaurea, Rubus, Taraxacum and 

 Hieracium, in which the ' British ' botanist or his Continental homologue 

 have described a multiplicity of species. In the case of Taraxacum and 

 Hieracium, the normal occurrence of parthenogenesis must surely entirely 

 modify our conception of so-called ' species ' in these genera, and make us 



" These records were made before the September droBght of 1929. 



