282 DR J. 351. MACFARLANE ON THE 



We have advanced reasons, drawn from microscopic study as well as from other points of 

 view, that Bryanthus erectus is a true hybrid, and that its reputed parentage is correct. 

 In the progress of horticulture, forms are continually appearing which are asserted to 

 be hybrids, and similarly as reputed wild species or varieties are being more carefully 

 scrutinised their hybrid nature is at times suggested. The great difficulty in safely 

 determining whether this is so has been the absence of sufficiently marked naked-eye 

 characters in the parents and hybrid. In a valuable contribution to hybridity by Mr 

 Meehan # many plants are mentioned which Linnaeus looked upon as hybrids between 

 species, but which he nevertheless described as species since the}^ freely reproduced 

 themselves. From a rather hasty study of some of these we should be inclined to 

 question Linnaeus' verdict in their case, but such forms as Trifolium hybridum, present 

 an apparently strong case for the systematise Armed now with an increased range 

 of characters for comparison, it should be possible to decide whether some at least have 

 not an undoubted relation to the supposed original parents. In such cases, nevertheless, 

 it must be kept in mind that if their origin dates back over a long period such changes may 

 subsequently have been effected in them by variation and selection that the comparison 

 can only be approximate, unless indeed one were to produce the hybrid artificially, and 

 find close microscopic resemblances between the natural and artificial types. In any case 

 we consider it as undoubted that recognition of hybrids from careful microscopic study 

 should now be possible in the great majority of cases. 



(i) The Possible Origin of Species from Hybrids. — When the literature of hybridity 

 perused from the historical standpoint one cannot fail to be impressed with the more 

 liberal spirit in which the subject is treated, and with the increasing belief in hybrids that 

 are tolerably, or even very fertile. Specially is this so on the botanical side, but a paper by 

 the late Francis DAY,t from the zoologists' standpoint, proves that great interest will 

 centre round the subject at no distant date. Hitherto it may be said that authorities, 

 with few exceptions, have declared wholly against the view that hybrids may be 

 sufficiently fertile, and their progeny sufficiently strong and adaptable to be fitted for 

 survival, not to say increase, in the struggle for existence. The admirable experiments 

 conducted by Wichura on willows go far to prove, one would think, that by the fourth 

 or fifth generation enfeeblement and decay become so marked that continued production 

 fails. But against this is to be placed the fact that many of our horticulturists are 

 ardent believers in the continued fertility of hybrids, as witness the article by Professor 

 Meehan already cited, though we believe that an over-sanguine expectation is some- 

 times entertained under this head. 



When one finds the undoubted hybrid between Geum rivale and G. urbanum 

 frequently described by systematists as a species, and that in many places the hybrid is 

 nearly or quite as abundant as either parent, that it freely produces good seeds, and further 

 that it has, as we have already indicated, many points of superiority as a combined 



* The Independent, No. 1063, New York, 

 t Proceedings of the Cotteswold Club, 1888-89. 



