572 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING. 



part of the substratum. Buds of Iris Kochii grafted on /. Flnniili mi produced 

 unaltered plants of /. Kochii, and buds of /. Florentina grafted on /. Kochii 

 developed simply plants of /. Florentina. In the Botanical Garden at Vienna 

 there is a male Ginkgo-tree {Ginkgo biloba) which, more than a hundred years 

 ago, was the subject of an important experiment. When the tree was still quite 

 small the hud of a female tree was grafted upon it by Jacquin, and a lateral branch 

 was developed from this bud. What we have now is a mighty tree with a number 

 of branches bearing male flowers, and one large branch bearing female flowers. The 

 notable thing about the tree is that the grafted branch follows a course of develop- 

 ment which is obviously different from that of the stock. Every year in the spring 

 it puts forth foliage about fourteen days later than the male branches, and in the 

 autumn its leaves are still green long after the rest have turned yellow and, for the 

 most part, fallen off. From this instance we may infer that the shoots developed 

 from the grafted bud adhere with the greatest tenacity even to individual charac- 

 teristics, and do not suffer the substratum to affect them even in respect of their 

 annual development. 



These facts have of recent years led many people to the opinion that the genesis 

 of graft-hybrids is simph' a gardener's story, and that even the most famous of the 

 supposed graft-hybrids — Cytisus Adami — does not owe its origin to budding, but 

 to a cross between Cytisus Laburnum and C. purpureus. Still, in view of the 

 curious mixing of the parent-characters in Cytisus Adami, as revealed by Mac- 

 farlane's investigations, it would perhaps be well to suspend our judgment. It is 

 true that even in true seed-hybrids (e.g. the Iris hybrids mentioned on p. 568) a 

 mixing (not a fusion) of the parental characters of the flowers was observed. Fresh 

 observations in this field are wanted, directed especially with a view to showing 

 whether or not the sum-total of the characters of Cytisus Adami are absolutely 

 unique amongst hybrid-plants of whatsoever origin. 



A further instance of the same nature may be mentioned, as it has been the 

 subject of careful scientific investigation and experiment. In 1876 a Jerusalem 

 Artichoke (Helianthus tuberosus) was grafted upon a Sunflower (Heliavth us 

 annuus) in the neighbourhood of Bristol, and it was alleged that as a consequence 

 the Sunflower stock had acquired from the Artichoke the property of producing 

 tubers on its subterranean portions. Quite lately a series of buds of the Artichoke 

 were grafted on Sunflower stalks by Vöchting, and the results carefully followed. 

 It was not found that the properties of the one were in any instance transmitted to 

 the other, although scion and stock grew together in perfect harmony. 



The importance of this subject is so great that I cannot refrain from trespassing 

 for a moment on the domain of Zoology in order to refer to a case which shows that 

 the animal world also sometimes affords instances of the characteristics of both 

 parents being manifested in juxtaposition in their hybrid-offspring instead of being 

 merged together or united in close combination. Tetrao medius is well known to 

 be a hybrid produced by a crossing between the Black grouse (Tetrao tetrix) and 

 the Capercailzie (Tetrao Urogallus). This hybrid is so common in Tyrol that the 



