294 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



FLORAL DEMONSTRATION. 

 By the Rev. Geo. Henslow, M.A., F.L.S., &c. 



[Given November 24, 1896.] 



Peofessoe Henslow first drew attention to a hybrid between 

 Primula obconica (pod-bearer) and the semi-wild form of 

 P. sinensis (pollen-bearer). Beyond having rather larger flowers 

 there was no visible character decidedly derived from P. sinensis. 

 The present plant was raised by Mr. Hyde, of Ealing. It 

 appeared to be a case of extreme prepotency on the part of the 

 mother plant. The lecturer alluded to the peculiar property of 

 P. obconica in its producing eczema on the hands of some 

 people. A somewhat analogous result accrues from handling 

 hyacinth bulbs. In the latter case, however, the result was due 

 to minute crystals in the cells of the scales. 



A collection of gloxinias, all bearing erect, trumpet- shaped 

 flowers, called for the remark that this form first appeared in 

 1846, and was known as G. Fyfiana. The original cross was not 

 known, but was probably itself a hybrid between G. speciosa 

 alba maxima and G. ccerulescens. It has always been the aim of 

 florists to convert " irregular " flowers (such as gloxinias, pansies, 

 pelargoniums, &c.) into regular ones, which botanists regard as 

 having been the primeval form from which irregular ones have 

 been derived ; but perhaps the effort is a doubtful advantage 

 in the case of the gloxinia. Mr. Henslow advanced his 

 theory of adaptation to account for the naturally irregular 

 form of many flowers, viz. that where the lower petal in 

 front is enlarged such enlargement has been due to the 

 responsive power of the living protoplasm of the plant to 

 meet the strain produced by the pressure of the insect upon 

 it. But where the insect visitor alights only on the stamens 

 of a flower, as in rhododendrons, amaryllis, veronica, horse 

 chestnut, &c, then the lower front petal tends to be atrophied 

 and is reduced in size or vanishes altogether, as in the horse 

 chestnut. As an illustration of response to strain, if a weight 

 be attached to a growing stem, just insufficient to break it, the 



