ORIGIN AND DEVELOPMENT OF THE COMPOSIT.i; 203 



ness, really Jiiuouiiting to virtual non-existence, of the geological 

 record, whether he has ever realised the errors a zoologist, in the 

 absence of fossilised remains, would most likely fall into who should 

 endeavour to apply that hypothesis to, say, the Mammalia ? And if 

 palpable mistakes would almost certainly be made in dealing Avith the 

 animal world, what assurance have we of safe ground for speculation 

 when plants are in question? In accordance with the hypothesis, 

 Dr. Small considers Senecio to be clearly marked out as priniitive on 

 account of its wide distribution in space. Gnaphalium is the only 

 genus, he says, which can claim anything like equality with Senecio 

 on this ground ; but here he overlooks Aster, for he cannot be un- 

 aware that the Southern Felicia and Olearia are merely geographical 

 offsets which have actually been included in Aster by botanists of 

 repute. The question then is where did this primitive genus arise ? 

 The centre of origin is indicated " by the coincidence of the region of 

 concentration of local species wdth" the region of the overlapping of 

 the areas of the widespread species," and this shows the centre of 

 origin of Seuecio (from a Lobelioid ancestor) to be the Bolivian 

 region. Similar conclusions drawn from present-day distribution are 

 put forward with respect to all the Composite tribes. These are pure 

 assumptions, which may be true in some cases and hopelessly 

 erroneous in others ; as applied to Senecio they do not seem very 

 happy. All _ that can safely be said is, that at some time after the 

 Andine uplift began, Senecio was represented in that part of the 

 world : the contingent earth-movements resulted in the formation of 

 hundreds of isolated valleys, thus bringing about conditions most 

 favourable to specific difi'erentiation. This would account for the 

 large number of Andine species, but it tells us nothing concerning 

 the first appearance, there or elsewhere, of the genus. 



The author's treatment of the pappus, although ingenious, is by 

 no means satisfactory. To say that the seta? are composed of hairs 

 variously united and to infer from this that all forms of pappus are 

 similarly composed, is surely to ask more than can be granted. And 

 when we find the main point evaded round which controversy has 

 raged — namely the homologies of the pappus — the only conclusion to 

 be drawn from the claim that the application by him " of a little 

 microscopy combined with an obvious application of elementary 

 i3hysiological facts removes the clouds of controversy " from this vexed 

 question is that he is the victim of delusion. 



Of course we have the inevitable phylogenetic tree; but why 

 Senecio should appear comfortably installed in the Upper Cretaceous 

 period when no remains attributable with any certainty to the genus 

 have been found in strata below the Pliocene, is known to Dr. Small 

 alone. But this is sobriety itself when compared with the last 

 chapter headed " The Story of the Compositce in Time and Space." 

 A short extract from this will give an idea of its tenour. '* Just as 

 its" \_Clmquir a guars'] "cousin, or rather niece, QliaptaUa raced along 

 the mountain ranges on regaining an efiicient pappus in a suitable 

 environment, so did Chuquiragiia. Like Chaptalia also, this new 

 genus was transformed on crossing the Alaska-Siberian bridge by an 

 increase in the corolla material, which was rendered ix)ssible by the 



