June 21, 19CXD] 



NATURE 



75 



best to touch upon individual papers rather than to 

 attempt to discuss them together under special headings, 

 as was done before. 



One must not pass over without mention the list of 

 some hundreds of hybrid plants exhibited at Chiswick on 

 the first day of the Conference. In this are given the 

 names of the parent species and of the raisers, as well as 

 notes as to characteristics and habits, and points in which 

 the hybrids most resemble their father or their mother. 

 The generic headings are arranged alphabetically, while 

 several plants and the pitchers of some Nepenthes are 

 figured. .\ page is further devoted to the interesting 

 series of mixed grafts which were also shown. In these 

 the branches of both scion and stock retain their foliage, 

 and in all cases the component plants belong to diflferent 

 genera. The title of " Hybrid Grafts," given to them in 

 the report, does not seem to be a satisfactory one, being 

 open as it is to misinterpreta- 

 tion or to confusion with " graft 

 hybrids." 



Dr. Masters' introductory ad- 

 dress has already appeared in 

 Nature (vol. Ix. p. 286). Among 

 Mr. Bateson's contentions as to 

 the origin of species, which have 

 not been previously alluded to, 

 is his statement that most pro- 

 fessed botanists and zoologists 

 are agreed that no natural 

 species, whether animal or 

 plant, has arisen by direct 

 hybridisation. This may be 

 mentioned, as another contri- 

 butor to the report expresses 

 the opposite opmion. Further- 

 more, Mr. Bateson's remarks as 

 to the benefits that many horti- 

 culturists might confer upon the 

 student of evolution, by record- 

 ing even rough statistics, are 

 very much to the point. 



The getiics Anthurium. — M. 

 de la Devansaye says : (i) that 

 in this genus, pollen to be of 

 value must come from plants 

 springing from a different batch 

 of seeds from that giving rise 

 to the ovule-bearing individuals ; 

 (2) that pollen from allied genera 

 has a beneficial eflfect ; (3) that 

 variations may not be seen in i 



the first or second generation of 

 hybrids, and yet may appear in 



the third or fourth. Hence experiments should not be 

 abandoned too soon. 



Monstrosities. — Prof. Hugo de Vries' paper, read under 

 the title of " Hybridisation as a means of Pangenetic 

 Injection," now appears as "Hybridisation of Monstrosi- 

 ties." There is plenty in it, however, which does not 

 refer to monstrous plants. Variation among hybrids of 

 the first generation, as regards the colour of the flower, 

 ■in a case considered by the professor, is put down by 

 him as justifying the supposition that they simply in- 

 herited their variability from their mother. He lays down 

 as a rule of horticultural practice the choosing of forms 

 to hybridise, of which at least one is known to be very 

 variable. The well-known multiformity of hybrids is 

 stated to arise from this, but the fact — abundantly proved 

 by the Conference— is also noted, that many hybrids can 

 hardly be distinguished exteriorly from one or other of 

 their parents, and therefore may be often mistaken for 

 true species. 



Hybridisation and its Failures. — Physiological affinity, 

 says Prof. Henslow, it would seem, must be neglected 



NO. 1599. VOL. 62] 



altogether in purely systematic work. He gives many 

 cases where plants that botanically are placed in separate 

 genera or families, on the strength of a single character, 

 will not breed together, and he contends that genera that 

 can be crossed should not be united for this reason alone, 

 for if interbreeding is to be the test, polymorphic forms 

 of the same species would logically have to be separated. 

 The many " failures " recorded by Prof. Henslow must 

 not be all put down as definitely proved to be such, as in 

 many cases adverse conditions, of which the experi- 

 menters were ignorant, may have prevailed. 



One would be interested to know whether the professor 

 gained much information from the answers to the ques- 

 tion set by him at the Royal Horticultural Society's 

 examination last year, which ran, " Give any instances of 

 failures, and state your opinion as to their causes, in 

 crossing distinct species.' 



Fig. I. — True anl fa'se hybrids of Citrus, 



Official Work of the United States. — In the previous 

 notice were mentioned the difficulties met with by Mr. 

 Webber and Mr. Swingle, owing to the ovule of Citrus pro- 

 ducing more than one embryo. In the accompanying 

 illustration (Fig. i), reproduced from the report by the 

 courtesy of the Royal Horticultural Society, pots i and 4 

 each contain two seedlings of Citrus trifoliata type, 

 arismg from a single seed, and which show no effiscts 

 of any cross. In the second pot are three young plants, 

 again rising from a single seed, as determined after it 

 had germinated. The seed was the result of a cross 

 between C trifoliata^ ^ , and the Tangerine orange, $ . 

 One of the seedlings has trifoliate leaves of larger size 

 than the typical C. trifoliata., and this is the true hybrid 

 from the egg-cell proper, while the other plantlets with 

 unifoliate leaves, and resembling the Tangerine, are from 

 adventive embryos. 



In No. 3, where the parents of the seed were the sweet 

 orange, $ , and C. trifoliata., ^ , two seedlings have grown 

 both with trifoliate leaves, and that having these larger 

 and more abundant may be put down as the hybrid. The 



