TBANSACTIONS OF SECTION D. 689 



they are copiously fertile, and when sown alone reproduce their rarietrJ form. 

 Not only have certain forms been imparted to other Ferns, but even variegation, 

 notably so in the Shield Fern and the Hart's-tongue. In the latter spores from a 

 normal but variegated form were sown thickly with a plumose (or crispum form) 

 and a branching form, and their offspring have become variegated. By sowing a 

 muriate and a plumose Hart's-tongue together, muriate plumose varieties have also 

 resulted. 



For illustrating multiple parentage the Hart's-tongue has been selected, as the 

 simple, strop-shaped fronds are best able to show the various departures from the 

 normal form. 



la repeating the experiment of mixed spores the varieties iu each case have' 

 been limited to three or four, so that the resultant changes could be more narrowly 

 investigated. Distinct mixtures were sown in 1887, 1888, 1889, and 1890, and 

 the results in all the experiments established the fact that the antheridia of more 

 than one variety have assisted in the impregnation. The varieties had con- 

 spicuously distinct characters, and in the example of 1888 tlie spores were 

 gathered from a dwarf spiral form, a muricate or warty form, an undulate and a 

 ramose one ; more exactly speaking, the varieties were sjji'rale, andidatum, muri- 

 catuni, and keratoides. The parents were exhibited as well as three of their 

 children, the latter having the names of quadriparens, Daruiniana, and echinatum. 

 These unmistakably show on each plant the characters of the whole four parents. 

 In the hundreds of these seedlings, as might be expected, the majniity show only 

 the characters of two parents, in a less though considerable number the characters 

 of three, whilst a small number exhibit those of the four parents. The plants in 

 the 1889 experiments are from a muricate, a branched, and a cup-bearing form, 

 known as ^era/erew.s, the object being to obtain cups on a branching muricate 

 Fern, as this was a desideratum. There was no previous example of more than 

 one cup on a frond. In the seedlings a divided frond can be observed with cups 

 on each division, a tasselled form with a rosette in place of an actual cup, and in 

 another example a marginal row of small cups ; and all are muricate. It is worth 

 remarking that the seedlings from mixed spores never seem to produce any plants • 

 that exactly resemble any one variety ; they are all combinations; in other words, 

 antherozoids from a number of ditierent antheridia are required for fertilisa- 

 tion. In sowing varieties of the Lady Fern I have raised the combination of five 

 and six. This is alluded to in my paper 'On Prothalli.' These plants that give 

 evidence of multiple parentage were obtained in the identical manner formulated 

 before they had any existence. Spores require to be sown thickly to enable the 

 prothalli to intermingle, otherwise they are only fertilised from the same prothallus. 

 If we take the reasoning of Sir John Herschel on the doctrine of probability, and 

 apply it to these experiments, the chances against the reasoning adopted being 

 incorrect are as great as that of the haphazard distribution of the stars. These 

 experiments regarding the changes in animal and vegetable life werecommenced 

 forty years ago. Bearing to some extent on this subject, experimenting on the 

 Mimulus, a yellow variety was crossed with a spotted one, and the seedlings were 

 spotted; later on, and further up the same stem, two blooms were this time 

 crossed with a yellow one, but the seedlings were still spotted. The efiect of the 

 first cross had become a part of the life-history of the plant ; in a second experi- 

 ment the same plant was simultaneously crossed with pollen from two other 

 Tarieties, and several of the seedlings are combinations of the three. It requires 

 dexterity in crossing the Mimulus, as the pistil is as sensitive as the sensitive 

 Mimosa. Natural changes are slow, but culturally we can accelerate that process 

 that continues age after age. The germ once changed, the new element is re- 

 tained, which becomes combined with others until the normal appearance is lost. 

 The illustration of the Hart's-tongue shows this alteration, helped on as it were by 

 artificial means that have accelerated the process, and these changes will continue 

 whilst the world lasts. Afl'ectionate respect causes tablets to be erected in 

 memory of the departed, but age obliterates this record. It is, however, far 

 different with the philosopher who has discovered great truths ; he has erected a 

 monument to himself ' more lasting than brass.' Time wears away the hardest 



1891. TT 



