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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY 



with few exceptions, are members of various hybrid series, whose further 

 development in conformity vAih. law is changed and hindered by frequent 

 crossings inter se. The circumstance must not be overlooked that 

 cultivated plants are mostly growTi in great numbers and close together, 

 which affords the most favourable conditions for reciprocal fertilisation 

 between the varieties present and the species itself. The probability of 

 this is supported by the fact that among the great array of variable forms 

 solitary examples are always -found, which in one character or another 

 remain constant, if only foreign influence be carefully excluded. These 

 forms develop precisely as do those which are known to be members of 

 the compound hybrid series. Also with the most susceptible of all cha- 

 racters, that of colour, it cannot escape the careful observer that in the 

 separate forms the inclination to vary is displayed in very different degrees. 

 Among plants which arise from 07ie spontaneous fertilisation there are 

 often some whose offspring vary widely in the constitution and arrange- 

 ment of the colours, while others furnish forms of little deviation, and 

 among a greater number solitary examples occur which transmit the colour 

 of the flowers unchanged to their offspring. The cultivated species of 

 Dianthus afford an instructive example of this. A white-flowered example 

 of Dianthus caryophyllus, which itself was derived from a white-flowered 

 variety, was shut up during its blooming period in a greenhouse ; the 

 numerous seeds obtained therefrom yielded plants entirely Avhite-flowered 

 like itself. A similar result was 'obtained from a subspecies, Avith red 

 flowers somewhat flushed with violet, and one with flowers white, striped 

 with red. Many others, on the other hand, which were similarly pro- 

 tected, yielded progeny which were more or less variously coloured and 

 marked. 



Whoever studies the colouration which results in decorative plants 

 from similar fertilisation can hardly escape the conviction that here 

 also the development follows a definite law which possibly finds its 

 expression in ihc combination of several independent colour characters. 



Concluding Remaeks. 



It can hardly fail to be of interest to compare the observations made 

 regarding Pisum with the results arrived at by the two authorities in this 

 branch of knowledge, Kolreuter and Gartner, in their investigations. 

 According to the opinion of both, the hybrids in outer appearance present 

 either a form intermediate between the original species, or they closely 

 resemble either the one or the other type, and sometimes can hardly be 

 discriminated from it. From their seeds usually arise, if the fertilisation 

 was effected by their oa\ti pollen, various forms which differ from the normal 

 type. As a rule, the majority of individuals obtained by one fertilisation 

 maintain the hybrid form, while some few others come more like the seed 

 IDarent, and one or the other individual approaches the pollen parent. This, 

 however, is not the case with all hybrids without exception. With some 

 the offspring have more nearly approached, some the one and some the other, 

 original stock, or they all incline more to one or the other side ; while with 

 others they remain perfectly like the hybrid and continue constant in 

 their offspring. The hybrids of varieties behave like hybrids of species, 



