September 25, 1896.] 



SCIENCE. 



439 



Another law whicli must be kept in 

 mind, also, is that evolution for the most 

 part has proceeded from the simple to the 

 complex. The simpler plants of to-day 

 represent to a large extent the types of the 

 primitive plants of former periods, from 

 which the complex plants of to-day were 

 derived. In this connection, however, we 

 must not overlook the fact, as pointed out 

 elsewhere,* that in the evolution of the suc- 

 cessive members of groups of plants there 

 has often been a simplification of structure. 

 Thus we often find apetalous derivatives 

 from polypetalous types ; bicarpellary ova- 

 ries from polycarpellary types; one-celled, 

 one-seeded, compound ovaries from several- 

 celled, many-seeded ovaries. But there is 

 a great difierence between these simplified 

 structures, which have been derived from 

 more complex structures, and those which 

 are primitively simple. The former are 

 nearer the end of a lengthened genetic line; 

 the latter are nearer its beginning. 



When we apply these principles to the 

 system to Bentham and Hooker we find no 

 contact points whatever between Monocoty- 

 ledons and Dicotyledons. The lower Mono- 

 cotyledons are very unlike any of the 

 Apetalse. What similarity, for example, is 

 there between the Grasses and Sedges on 

 the one hand, and the Oak, Walnut and 

 Plane Trees on the other. It is only when 

 we pass up to the Apocarpce in the Monocoty- 

 ledons, and to the Micrembryece and possibly 

 Piperaceoe of the latter, there are many simi- 

 larities of structure. To this reference must 

 be made later, and it need only be said here 

 that evidently the authors made no attempt 

 to indicate by their arrangement of families 

 any contact point between the Monocotyle- 

 dons and Dicotyledons. 



In the system of Engler and Prantl one 

 might look for such a disposition of the 



* 'Evolution and Classification,' Proc. A. A. A. S., 

 Vol. XLII., and 'The Significance of the Compound 

 Ovary, ' presented at this meeting. 



families of the two sub-classes as to indi- 

 cate a common point of origin, but in this 

 we are disappointed. When we compare 

 the structure of the families placed at the 

 beginning of the Monocotyledons, viz : the 

 Typhacece, Pandanacem, Sparganiacece, Pota- 

 mogetonacece, Naiadaeece, Aponogetonacece, Alis- 

 macece, etc., with those occupying a similar 

 place in the Dicotyledons, viz : Saururacece, 

 Piperacece, Chloranthacece, Lacistemacece, Jug- 

 landacece, Ilyricacece, Leitneriacece, Salicacece, 

 etc., it is at once evident that here there is 

 a great gulf between the two sub-classes. 

 It is becoming more and more evident that 

 this system, which promised so much, is lit- 

 tle better as an expression of genetic rela- 

 tionship than the system of Bentham and 

 Hooker, which it is now displacing. Its so- 

 called lower families are for the most part 

 composed of plants with not a simple, that 

 is, a primitive structure, but a simplified 

 structure. As a rational system, designed 

 to express our ideas of genetic relationship, 

 it is sadly disappointing. 



It is evident that we must cease to con- 

 fuse the simplified with the primitively 

 simple structures, and that in the latter 

 alone can we find the point of divergence 

 of the plants of the two sub-classes under 

 consideration. It is only when we do this 

 that we are able to construct a system 

 which shall suggest to us the solution of the 

 problem. Our system must begin with 

 simple pistils, not compound pistils — with 

 really simple and simplified pistils. It 

 matters little whether the flowers are per- 

 fect or not ; whether they have many or 

 few flowers-leaves, or even none at all. 

 We have learned that these are minor mat- 

 ters, and that they change very readily 

 even within narrow limits. 



In accordance with these principles we 

 may readily fix upon the apocarpous Mo- 

 nocotyledons (Bentham and Hooker's Apo- 

 carpoi) as the representatives of the primi- 

 tive members of this sub-class. This struc- 



