466 



SCIENCE. 



[N. S. Vol. XII. No. 300. 



sil in the oldest strata of all, the Archsean, 

 is the much- discussed Eozoon canadense, 

 probably of animal origin ; but the occur- 

 rence here of large deposits of graphite 

 seems to indicate the existence of a consid- 

 erable flora which has, unfortunately, be- 

 come quite undeterminable. Thus, whilst 

 there is some evidence that the primitive 

 plants were Algse, there is at present no 

 available record of the various stages 

 through which the Silurian and Devonian 

 vascular plants were evolved from them. 



MORPHOLOGY. 



If inquiry be made as to the cans e of the 

 great advance in the recognition of the true 

 affinities of plants, and consequently in their 

 classification, which distinguishes the nine- 

 teenth century, I would refer it to the prog- 

 ress made in the study of morphology. 

 The earlier botanists regarded all the 

 various parts of plants as ' organs ' in re- 

 lation to their supposed function ; hence 

 their description of plants was simply ' or- 

 ganography.' The idea of regarding the 

 parts of the plant- body, not in connection 

 with their functions, but with reference to 

 their development and their mutual rela- 

 tions, seems to have originated with Jung 

 in the seventeenth century (1687): it was 

 revived by C. F. Wolff about seventy years 

 later (1759), but it did not materially af- 

 fect the study of plants until well on in the 

 nineteenth century, after Goethe had re- 

 peatedly written on the subject and had de- 

 vised the term ' morphology ' to designate 

 it. For a time this somewhat abstract 

 mode of treatment led to mere theorizing 

 and speculation, so much so that the years 

 1820-184:0 will always be stigmatized as 

 the period of the ' Ifaturphilosophie.' But 

 fortunately this time of barrenness was 

 succeeded by a veritable renascence. Eob- 

 ert Brown and Henfrey in England ; Brong- 

 niart, St. Hilaire, and Tulasne in France ; 

 Mohl, Schleiden, Naegeli, A. Braun and 



above all Hofmeister in Germany, led the 

 way back from the pursuit of fantastic will- 

 o'-the-wisps to the observation of actual 

 fact. Instead of evolving schemes out of 

 their own internal consciousness as to how 

 plants ought to be constructed, they en- 

 deavored to discover by the study of de- 

 velopment, and more particularly of em- 

 bryogeny,how they actually are constructed, 

 with the result that within a decade Hof- 

 meister discovered the alternation of gen- 

 erations in the higher plants ; a discovery 

 which must ever rank as one of the most 

 brilliant triumphs of morphological re- 

 search. 



With the knowledge thus acquired it be- 

 came possible to determine the true relations 

 of the various parts of the plant-body ; to 

 distinguish these parts as ' members ' rather 

 than as ' organs ' ; in a word, to establish 

 homologies where hitherto only analogies 

 had been traced — which is the essential dif- 

 ference between morphology and organog- 

 raphy. 



The publication of the ' Origin of Species ' 

 profoundly aifected the progress of mor- 

 phology, as of all branches of biological re- 

 search ; but it did not alter its trend ; it 

 confirmed and extended it. We are not 

 satisfied now with establishing homologies, 

 but we go on to inquire into the origin and 

 phj'logeny of the members of the body. In 

 illustration I maj' briefly refer to two prob- 

 lems of this kind which at the present time 

 are agitating the botanical world. The 

 first is as to the origin of the alternation 

 of generations. Did it come about by the 

 modification of the sexual generation (game- 

 tophj^te) into an asexual (sporophj'te) ; or 

 is the sporophyte a new formation inter- 

 calated into the life-history ? In a word, is 

 the alternation of generations to be regarded 

 as homologous or as antithetic? I am not 

 rash enough to express any opinion on this 

 controversy ; nor is it necessary that I 

 should do so, since the subject has twice 



