Henslow^s Examinaticm of a hybrid Digitalis. 209 



actions of the Cambridge Philosophical Societi/. The pamphlet has no 

 publisher's name affixed to it, and is probably not for sale. 



Hybridising is the art of imbuing the ovules of one plant with the 

 additional or distinct properties of some other plant. From Digitalis lutea 

 impregnated by D. purpurea, Professor Henslow obtained a decided 

 hybrid, " obviously having most of its characters exactly intermediate 

 between those of purpurea and those of lutea." This is the fact which 

 forms the theme of the professor's most able pamphlet; for although in the 

 fact itself there is nothing surprising, now that hybrids in various genera 

 are familiar to all gardeners, the inferences the professor draws from this 

 fact, and the modifications in structure which he shows the hybrid to have 

 undergone in almost every one of its parts, render the pamphlet a most 

 important contribution to physiological botany. We hope our gardening 

 friends will be stimulated by the following polite reproof so to change the 

 state of things as never to merit a second such. " Although," the professor 

 remarks, " the propagation of hybrid plants has been much attended to of 

 late years by several horticulturists in England, their experiments for the 

 most part seem to have been undertaken tor the sole object of increasing 

 the forms of beautiful flowers, or of modifying the flavours of delicious 

 fruits. But the more curious and important physiological facts, elicited 

 by the phenomenon of hybrid productions, do not appear to have received 

 a proportionate degree of attention from those who have been engaged in 

 these experiments." 



" Chance having favoured me with a hybrid Digitalis during the summer 

 of 1831, in my own garden, I employed myself, whilst it continued to 

 flower, which was from June 19. to July 22. in daily examining its cha- 

 racters, and anatomising its parts of fructification. I was careful to com- 

 pare my observations, with as much patience and accuracy as I can com- 

 mand, with the structure of its two parents. It seemed to me not unlikely 

 that something interesting might result from a rigorous examination of this 

 kind, or at least that its recorded details might serve as a point of depar- 

 ture for future observations." 



Something indeed interesting has resulted ; a stock of facts of the 

 highest importance to physiologists has been elicited ; and the details have 

 been elaborated, described in words, and illustrated by engravings, to an 

 extent marvellous for the patience and the industry they must have de- 

 manded. This will be clear to our readers when we remark that the 

 detailed descriptions of, and observations on, the various parts of the 

 plants, not omitting the most minute parts which very high magnifying 

 powers could elucidate, occupy twenty quarto pages ; and the various 

 figm'es of parts, some whole, some dissected, some of the natural size, 

 but the majority highly and some very highly magnified, occupy three 

 quarto plates ; and there is, besides, a folio plate exhibiting the raceme and 

 a leaf of the hybrid, the subject of the book. We shall not further notice 

 all these than as to their amount, which, as stated above, is that the hybrid 

 participates equally all the external characters of its two parents ; as slight 

 exceptions, however, the stigma in its shape resembles that of neither, and 

 the corolla in the hybrid falls off before the anthers vyhich it bears have 

 parted with their pollen, and the hybrid is, in consequence, barren of seed ; 

 this, in both parents, is not the case, which are consequently sufficiently 

 fertile of seeds. In examining the internal organisation of the three plants 

 in their various parts, the professor has been unable to detect any differ- 

 ence ; but his researches have enabled him to show the high beauty and 

 admirableness of the anatomical details of these parts. We shall only 

 notice further the ingenious and convenient mode in which Professor 

 Henslow has displayed his descriptive details for the sake of prompt 

 comparison. It is this : — 



Vol. VIII. — No. 37. p 



