Chap. XL GRAFT-HYBRIDS. 415 



better state, and included very few shrivelled grains. Although the 

 pollen of the reverted purple flowers was in so poor a condition, 

 the ovules were well formed, and the seeds, when mature, germi- 

 nated freely with me. Mr. Herbert raised plants from seeds of 

 the reverted purple flowers, and they differed a very little from the 

 usual state of C. purpureus. Some which I raised in the same 

 manner did not differ at all, either in the character of their flowers or 

 of the whole bush, from the pure C. purpureus. 



Prof. Caspary has examined the ovules of the dingy-red and 

 sterile flowers in several plants of C. adami on the Continent, 93 and 

 finds them generally monstrous. In three plants examined by me 

 in England, the ovules were likewise monstrous, the nucleus 

 varying much in shape, and projecting irregularly beyond the 

 proper coats. The pollen grains, on the other hand, judging from 

 their external appearance, were remarkably good, and readily pro- 

 truded their tubes. By repeatedly counting, under the microscope, 

 the proportional number of bad grains, Prof. Caspary ascertained 

 that only 25 per cent, were bad, which is a less proportion than in 

 the pollen of three pure species of Cytisus in their cultivated state, 

 viz., C. purpureas, laburnum, and alpinus. Although the pollen of 

 C. adami is thus in appearance good, it does not follow, accord- 

 ing to M. Naudin's observation 94 on Mirabilis, that it would be 

 functionally effective. The fact of the ovules of C. adami being 

 monstrous, and the pollen apparently sound, is all the more re- 

 markable, because it is opposed to what usually occurs not only 

 with most hybrids, 95 but with two hybrids in the same genus, 

 namely in G. purpureo-elongatus, and C. alpino-laburnum. In both 

 these hybrids, the ovules, as observed by Prof. Caspary and myself, 

 were well-formed, whilst many of the pollen-grains were ill-formed; 

 in the latter hybrid 20"3 per cent., and in the former no less than 

 84 - 8 per cent, of the grains were ascertained by Prof. Caspary to be 

 bad. This unusual condition of the male and female reproductive 

 elements in 0. adami has been used by Prof. Caspary as an argu- 

 ment against this plant being considered as an ordinary hybrid 

 produced from seed ; but we should remember that with hybrids 

 the ovules have not been examined nearly so frequently as the 

 pollen, and they may be much oftener imperfect than is generally 

 supposed. Dr. E. Bornet, of Antibes, informs me (through Mr. J. 

 Traherne Moggridge) that with hybrid Cisti the ovarium is fre- 

 quently deformed, the ovules being in some cases quite absent, and 

 in other cases incapable of fertilisation. 



Several theories have been propounded to account for the origin 

 of C. adami, and for the transformations which it undergoes. The 



93 See ' Transact, of Hort. Congress 94 ' NouveHes Archives du Alu- 



of Amsterdam,' 1865 ; but I owe seum,' torn. i. p. 143. 

 most of the following information to 95 See on this head, Xaudin, ibid., 



i'rof. Caspary's letters. p. 141. 



