228 Mr. William Brockbank on 



about by this cross. 5. Macnabiana seldom exceeds halt 

 the height of 5. Cotyledon. Its leaves are also much 

 smaller. A fine flower scape will number over a hundred 

 flowers. One fine plant of 5. nepalensis, in flower at Brock- 

 hurst in 1883, carried 44 branches from the centre stalk, 

 each having from 12 to 22 flowers, so that there were about 

 750 flowers, each the size of a fourpenny-piece, in one panicle 

 of bloom. Now as these flowers occur in succession, it will 

 be clear that there may be considerable variety in the time 

 of ripening of the flowers, and thus there is room for great 

 divergence. 



In 1886 a fine scape of 5. Macnabiana ripened its 

 seed in my garden, and a quantity was saved from it. 

 This was sown, and produced a large crop of plants. It 

 was soon noticed that there were great differences amongst 

 the seedlings, and these increased as the plants grew. The 

 most notable were therefore separated, and were grown on 

 in small pots, and of these 1 10 varieties are now exhibited ; 

 every one resulting from the seed of this one single scape. 

 In the garden where the plant grew there were nearly all 

 the known species and varieties of saxifrage, at least 150 ; 

 and, therefore, it is possible enough that pollen from a 

 great variety of saxifrages might be carried by insects to 

 the mother plant. Likenesses are evident, amongst the 

 1 10 seedlings, to the following species and varieties of 

 Saxifraga: — lingulata, Hostii, crnstata, pectinata, elatior, 

 carinthiaca, Cotyledon, Aiaoon, and Gnthreana. 



Here then we have a remarkable illustration of the 

 multiplication of varieties from a single scape of bloom ; 

 and it affords an excellent example of the truth of 

 Darwin's investigations on the fertilization of plants by 

 insects. 



Sprengel was, I believe, the first to point out that many 

 flowers were fertilized by insects ; and Andrew Knight 

 showed that in no plant does self-fertilization occur for an 



