32 



Garden and Forest. 



[Number 413. 



intelligence. The experiment stations are doing- much for 

 cultivators of the soil by publishing the results of scientific 

 research and making experiments which are too costly for 

 farmers to carry out. But the hope of agriculture in the 

 future in this country must rest, after all, on a wider 

 system of education. The rural industries will prosper 

 just as the whole rural population becomes more enlight- 

 ened and are enabled to bring to their daily work minds 

 drilled and equipped for active thinking as well as muscles 

 trained and strengthened for expert handiwork. 



The latest and forty-eighth volume of The Garden is 

 dedicated to George Nicholson, curator of the Royal Gar- 

 dens at Kew, for his work among trees and shrubs. In his 

 dedication the editor takes occasion to state that " we do 

 but express the general feeling of the horticultural world 

 toward the important national establishment of which Mr. 

 Nicholson is the distinguished practical head. We recog- 

 nize with considerable pleasure the great improvement in 

 the present cultivation and disposition of the collections at 

 Kew compared with past times, an improvement due to 

 the proper recognition of the general desire to see pic- 

 turesque and artistic gardening in the nation's own garden 

 as well as the purely botanical. We believe this has been 

 accomplished without any loss on the botanical side ; 

 indeed, we learn that the collections are now much richer 

 in species, as well as in botanical interest, than ever they 

 were. Every gardener is grateful for this improvement at 

 Kew which we owe to the present staff of which Mr. Nich- 

 olson is a distinguished member, having been appointed 

 curator at the same time as Mr. T. Thiselton Dyer was 

 appointed director on the retirement of Sir Joseph Hooker 

 in 1886." In this country Mr. Nicholson is well known as 

 editor of the useful Dictionary 0/ Gardening. In 1893 he 

 visited the United States as a judge in the Horticultural 

 Department of the Chicago Exposition and made many 

 friends here. 



Early Experiments in Crossing Plants. 



IN the reference to Thomas Andrew Knight and his work 

 in Garden and Forest Qf December 25th, p. 512, a 

 statement is made from which a wrong conclusion may be 

 drawn. Professor Bailey is reported as saying : " He was 

 the first man, so far as I know, who advised the use of 

 cross-fertilization for the purpose of producing new varie- 

 ties and for the purpose of improving existing ones. A 

 similar work was taken up by Darwin." The emphasis 

 may be on Knight's important work in experimenting with 

 varieties which already existed rather than in the produc- 

 tion of new varieties by the crossing of species. But the 

 coupling of the name with that of Darwin seems to refer to 

 cross-fertilization in general, for Darwin experimented both 

 with species and varieties. Possibly a distinction is made 

 between a hybrid, between different species and a cross 

 between different varieties, but this is scarcely valid on the 

 scientific side. Nageli has said of it : "This distinction may 

 sometimes serve a practical purpose, but is frequently con- 

 fusing and deceptive, for it supposes a difference that is 

 merely one of degree." * However this may be, Kohlreuter, 

 an earlier experimenter than Knight, also used varieties as 

 well as species in his extended investigations on cross-fer- 

 tilization, and so anticipated Knight in this respect also. 

 His object differed from Knight's, for it was to prove the 

 sexual nature of plants, a question about which botanists 

 were still contending. Like Darwin's experiments in cross- 

 fertilizing plants to prove his theory of the origin of species, 

 Kohlreuter's work was almost purely scientific in its aim, 

 but he was a pioneer in what has proved of immense prac- 

 tical benefit. Some account of his earliest work, and that 

 of Linnseus, along similar lines, may be of interest. 



Kohlreuter was a Swabian, born at Sulz, on the Necker, 

 where he produced his first hybrid plant in 1760. In 1764 



he was made Professor of Natural History in Carlsruhe, a 

 chair which he held till his death in 1806. Detailed accounts 

 of his earliest work were published at Leipsic at different 

 times from 1761 to 1 766.J The results of subsequent ex- 

 periments appeared in the Transactions of the Imperial 

 Academy of Sciences of St. Petersburg. Like the work of 

 Conrad Sprengel on the agency of insects in fertilizing flow- 

 ers — in which he was anticipated by Kohlreuter — published 

 in 1793, his experiments for a time passed out of sight or 

 attracted but slight attention. The revived interest in the 

 subject from the labors of Knight and Herbert in England, 

 Gaertner and Wiegman in Germany, Godron in France, 

 not to mention others, called attention to them once more. 

 Knight's efforts to improve fruits and vegetables, which 

 began about 1787, were evidently made in ignorance of 

 what Kohlreuter had done, and his discoveries were to 

 that extent independent. So scholarly a man as the Rev. 

 William Herbert, who did much splendid work in crossing 

 plants, says that he began his investigations " ignorant of 

 the experiments of Kohlreuter." He gave the first account 

 of his investigations before the Horticultural Society of 

 London in 1819. | Kohlreuter's work, being purely scien- 

 tific in its character, did not enlist the cooperation of horti- 

 culturists like the later work of Knight and Herbert, which 

 had, or was soon given, a practical bearing. Botanists, 

 being mostly devoted to systematic botany, were indifferent 

 or even opposed to such labors. This attitude of botanists 

 and failure of horticulturists to see the bearings of such 

 experiments on their art, may to some extent explain the 

 temporary oblivion into which Kohlreuter's earlier work 

 passed. 



His first success was in crossing Nicotiana paniculata 

 and N. rustica. From the seed produced other plants were 

 raised. Various other experiments followed, sometimes 

 with varieties of one species, more frequently by crossing 

 different species. Though some of the conclusions he 

 derived from his experiments have proved erroneous, 

 partly because he mixed up certain a priori ideas with 

 them, to him is largely due the credit of placing the theory 

 of the sexuality of plants on a firm foundation. Little 

 ground for doubt was left after his careful experimentation, 

 conducted on the strictest scientific lines, and the sex of 

 plants became a fact without dispute, though it had been 

 broached as far back as the time of Aristotle. Kohlreuter 

 claimed that this Nicotiana cross was the first one arti- 

 ficially produced to which absolute credit could be given. 

 There was a bare possibility of their spontaneous produc- 

 tion among plants in a wild state, but the antecedent 

 probabilities were against it. 



Prepossessions, based partly on such ideas, partly on the 

 great infertility of hybrids and their tendency to revert to 

 one of the parent species, especially when left under con- 

 ditions to be fertilized by their pollen, hardly left Kohlreu- 

 ter in a state of mind to do full justice to Linnseus, who 

 was also investigating this subject. The great Swedish 

 naturalist had a lively imagination and drew too much 

 upon it, but every case of the crossing of plants he and his 

 pupils discovered or artificially made cannot be disproved 

 as easily as Kohlreuter and others have thought they 

 might be, so he sets aside the claim of Linnaeus to the 

 production of a hybrid Goat's-beard in 1759, calling it but 

 a half hybrid at the most. 



In 1757 Linnaeus found a Tragopogon in his garden, 

 which he named T. hybridus. It sprang up in a bed 

 where he had planted T. pratensis and T. parvifolius. 

 Winter came on before the seed matured, and he was not 

 able to test its power of reproduction. The next year he 

 fertilized the plants artificially. He removed the pollen of 

 T pratensis by rubbing it off early in the morning, and a 

 little later in the day brought pollen from T. parvifolius to 



* Botanische Mittlieilitngen, vol. ii., p. 188 (note), in an essay on " Die Bastard- 

 bildung im Pflan^enreiche." 



t Dr. Joseph Gottleib Kohlreuter's Vorlanfige NachricJU von einigen das Geschlecht 

 der PJlauzen betreffenden Versuckeu und Beobachtungen* (Reissued by Engelmann.) 

 Leipzig, 1893. 



+ All the references in Herbert's book on the Amaryllidaceae and its supplement 

 (London, 1837) are to the acts of the St. Petersburg Academy, unless a doubtful 

 allusion to " one concerning Nicotiana" is to those begun in 1761. 



