1 It) Til 1< .i<>u;\ A I. OF B< HA NT 



plant and animal phyla, without necessarily affording any reason 

 why they should be so. Jusl as, for example, as a simple matter 

 of observation, tbe highest animals still retain in the spermatozoon a 

 functional relic of the ancient plankton-phase of the sea, remote 

 beyond even any incipient aggregation of protoplasts to a multi- 

 cellular soma *-. To what extent absolute reliance may be placed on 

 this suggestion, is a point in question; but there can be little doubt 

 that it has been customaxy in botany, for the last generation or two, 

 to attribute an exaggerated importance to anything that could be put 

 forward as implying sexual relations-, again, as the inheritance of a 

 time not so very far hack when cytological sexuality in plants was 

 still a novelty 1 ', the more miraculous and therefore the more im- 

 portant as the details and their precise significance were the more 

 minute and often obscure. As a matter of fact, it is only within 

 the present century that the relations of such mechanism have 

 become sufficiently intelligible for one to obtain a comprehensive 

 view of such racial organization and the part it plays in the story of 

 the individual life. At the same time it will be evident that the 

 more complex the mechanism of reproduction, the more likely it will 

 be to present evidence of accurate adjustment to changes of the 

 environment, as determined by the life-and-death sorting-process of 

 natural selection, and the firmer such details will be ultimately 

 established as racial constants, which may he altered and modified 

 almost beyond recognition, but randy wholly lost. 



Lichens as a class are admittedly a branch of the great Asco- 

 myceto series of Fungi, using the term in the more general sense of 

 heterotrophic plant-forms in which the most characteristic repro- 

 ductive organ is distinguished as an ascus, with an output of normally 

 8 immobile spores, following an act of meiosis. The relation of 

 this asexual construction to the familiar 'unilocular sporangium' of 

 marine alga? ( Plneosporeae, Florideae) is so close, and is expressed in 

 such general terms, that the mere presence of this type of organ, 

 without confirmatory evidence in other respects, can afford no sure 

 mark of actual relationship. The fact that the conventional series 

 of Ascomycetes may he really an aggregate of many older polyphy- 

 letic lines of descent, convergent in the production of an asexual 

 sporangium of a certain limiting character, must not be forgotten *. 



I. The Case of tin; so-called Basidiojiycete-Lichex 

 (Mattirolo, 1881), 



Though hailed with great enthusiasm as affording the final proof 

 (if one were needed) of the dual nature of the composite const ruc- 

 tion 5 , this is really of minor importance. The phenomena of intrusion 

 are of a very elementary order ; the best examples (Cora) 6 are obviously 



1 ' The Building- of an Autotrophic Flagellate,' Bot. Mem. i. 1919, p. 14. 



2 Sachs (1874) Textbook, Em?. Trans. (1882) p. 284, ' Carposporeaj.' 



3 Hofmeister (1851) for the Pern, Bornet and Thuret (1854) for Fucus. 



4 Strasburger (Eng\ Trans. 1912) Textbook of Botany, \\. 389. Reliance on 

 cytological details proves equally illusory. 



5 De Bary, Comp. Morph. Fungi (Eng. Trans. 1887), p. 419. 



6 Zahlbruchner (1907, in Engler and Prantl), p, 239 ; Cora can live without 

 the alga. 



