456 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



by having one sepal spurred, and two petals with nectariferous append- 

 ages included within the spur of the sepal. In the double forms the 

 sepals are regular and the petals multiplied, and all are without the 

 appendages. The first step is for the flower to revert to the ancestral 

 condition of regularity without spur or nectaries, and the second to 

 multiply the petals. 



Gladiolus and Montbretia. — These two genera belong to the 

 same family as the Iris (Iridea). They both have "guides," consisting 

 of deeply coloured streaks or spots indicating the direction leading to the 

 honey ; but while the irregularity is more pronounced in the Gladiolus, 

 the "guide" is limited to the front leaves of the perianth. Montbretia 

 being more nearly regular, the dark spots are distributed more evenly 

 round the base of the perianth-leaves. In the trumpet-shaped flowers of 

 Gloxinia, now raised by florists, not only has the form of the flower 

 become perfectly regular and symmetrical in shape, but the colours are 

 also equally distributed. 



Gypsophila paniculata, fl. pi. — A new plant to cultivation is the 

 double form of this favourite, exhibited by Mr. Johnson, and one likely 

 to prove useful, as the flowers remain so much longer than do the 

 single. 



Pentstemox, Mimulus cardinalis, Verbascum and Salpiglossis 

 are plants which illustrate difficulties which systematic botanists meet 

 ydih. in classifying plants. The first three are included in Scrophu- 

 larinccB, which is well illustrated by the Foxglove and Snapdragon, and 

 characterised by having only four stamens, two of which have long 

 filaments and two have short ones. Pcntstcmon, however, as the name 

 implies, has five ; but one bears no pollen. In the Mulleins (Verbascum) 

 there are also five, and the posterior one is barren ; moreover the corolla 

 is nearly regular. Saljnglossis has been placed in three different orders 

 by botanists ! It now rests, according to Gen. PL, in the Potato family, 

 SolanacecB. 



A regular corolla with five stamens is characteristic of the family 

 SolanacecB, which contain the Potato and Deadly Nightshade. Hence the 

 above genera represent transitional or intermediate forms. 



It was the discovery of a vast number of such, both between species 

 of plants and animals, that led to the establishment of the doctrine of 

 Evolution. For although, when few plants and animals were known, they 

 seemed very distinct and easily defined, as knowlege of organised beings 

 increased the different kinds were often linked by such fine gradations 

 that the idea of their having been separately created was proportionally 

 improbable ; and that they had been evolved one from another was far 

 more likely. The late Mr. G. Bentham, in working up the CompositcR 

 for the " Genera Plantarum," said that he could not find any well-defined 

 character for separating no less than ninety genera in the tribe 

 Asteroidcce. 



Canna and Water-lily. — These genera, the former a Monocotyledon, 

 and the latter a Dicotyledon, illustrate the method adopted by nature of 

 making petals out of stamens ; for although this is ob^'ious in the case 

 of double flowers, as may be readily observed in a semi-double Rose, for 

 example, yet such are abnormal cases ; but in that of the above genera 



