June 14, 1906] 



NA rURE 



'47 



(lirirnnic " it becomes necessary to go further and to 

 .iMiriiiiii which phenomenon is exemplified in each 

 CISC. That genetic analysis can alone answer that 

 (.liuslion everyone now perceives. I)e \'ries' own dis- 

 cussion of his results contains manifest traces of an 

 • utinipt to incorporate the Mendelian ideas into earlier 

 and pro-Mendelian conceptions, and the result is not 

 always harmonious or convincing. We look to de 

 \ries and the many observers who are now at work 

 on CKnothera to bring the various possibilities to a 

 strict test, case by case, and so complete what has 

 been begun with such astonishing success. 



Meanwhile, however, it must be conceded that there 

 are serious ditlicultics in the way of a purely Mendelian 

 account of the Qinotheras — more perhaps than Prof. 

 Lotsv indicates. Of these one of the most formidable 

 is the behaviour of the form iianella, for which other 

 cases afford no parallel. There are, further, the 

 objections de Vries himself has urged in the passages 

 contributed to Moll's exposition of his work — particu- 

 larlv, that no indication of a hybrid origin of his 

 original stock is forthcoming. .Again, though the 

 slcrilc pollen grains are suspicious, I may mention that 

 in a collection of wild Qinotheras (? species) made near 

 Baltimore, I found none which had not some bad 

 pollen grains. W'erc all these hybrids? it may well be 

 asked. If .so, hybrids of what? Our Rubi hybridise 

 freelv, but, as Focke showed, there are pure forms 

 with perfect pollen, and hybrid forms with an ad- 

 mixture of bad grains. This test should be made in 

 .\merica on a large scale, to discover whether any 

 (l""nothcra is " pure " by that criterion. 



But again, we know that the production of analyti- 

 c d varieties by a hybrid, and the production of novel 

 forms by a mutating species, must be exceedingly 

 similar and perhaps indistinguishable phenomena. 

 Hybridisation cannot be regarded as the sole source 

 (if analytical variation — witness the case of Primula 

 sinensis and the sweet pea, where analytical variation 

 is rife, though no hybridisation has taken place. 

 The interrelationship of the two sets of occurrences 

 is still obscure ; but by experimental breeding it can 

 in great measure be elucidated, and in the course of 

 that inquiry the meaning of mutation will probably 

 be discovered. 



Only salient features of the book have been men- 

 tioned ; many others must be passed over. Capsella 

 has provided (p. iSo), as might be expected, good 

 examples of the constancy of petites especes. Time 

 brings revenges, and we must hope that Jordan would 

 have felt satisfaction in the recognition now accorded 

 to his once discredited work, though, bv the per- 

 versity of things, that work is used to complete and 

 support those views he most detested. Strange, too, 

 would it seem to his opponents to see Jordan's micro- 

 species received as a valuable cleinent in the general 

 doctrine of mutability ! 



In several minor points the book is open to criticism. 

 Tlie .\rtemia-Branchipus story should not be repeated 

 even incidentally without words of caution. The pic- 

 tures even in these half-tone days are below the mark, 

 and such pictures as those of peloric Linaria make one 

 NO. 191 I, VOL. 74] 



long for decent woodcuts again. The figure of the 

 Norwich canary would surprise the fanciers of that 

 city, and it suggests that the cr('st is a Norwich char- 

 acter. Lastly there is a profusion of most distracting 

 misprints. W. Bateson. 



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