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(in plants only) into spore-mother-cells plus sterilized spore-mo ther- 

 cell homologues (Bower). It is customary in plant morphology to 

 term the cellular product of indirect division the sporophyte. It 

 should be noted, however, that sporophytes are not all homologues of 

 each other, those of the Basidiomycetes for example having originated 

 independently from those of the Muscineae. The homologous series 

 of sporophytes extending from Oedogonium and Coleochaete to the 

 higher archegoniates and metaspermic plants is the best known, but 

 indirect divisions of the syngamete are known outside the archegoniate 

 phylum both in Algae and Fungi. 



In Metazoans this indirect division of the egg is extremely rare 

 and one finds the best examples of it in the experimental results of 

 Driesch, Roux, Hertwig and Wilson — to select a few from several 

 names. Wilson, to instance one case, found that the egg of Amphioxus 

 might in the early segmentation stages be separated into two, four 

 or eight blastomeres and that each of these might then develop into 

 a separate individual. I take it that this is what normally happens 

 in Oedogonium. The syngamete undergoes rejuvenescence and divides 

 into four zoospores (coenogenetic spores) each of which may form a new 

 individual of the sexual type. 



Now the profound diflerence between metazoan and metaphytic 

 reproduction lies is the fact that in plants the group of isolated 

 blastomeres (coenogenetic spores) in laid hold of by natural selection 

 as a group and is improved and integrated, some cells being steri- 

 lized, others retaining the ability to develop into a new sexual indi- 

 vidual. Hence appears the sporophyte which attains vegetative inde- 

 pendence in ferns and higher plants. The sterilized cells sometimes 

 resume the spore function — as for example where the cells of a 

 moss-sporophyte, as shown by Pringsheim, develop protonema. More 

 commonly such atavism is unknown. But in animals such isolated 

 blastomeres when obtained are not redintegrated into an antithetic indi- 

 vidual. It will be seen that this Iview is thoroughly in accord with 

 the known facts regarding reduction of chromosomes in plants and 

 animals, nor is it necessary to postulate any antithetic alternation in 

 Metazoans whatever. 



Here, however, I can not refrain from a word of caution to those 

 who are inclined to base weighty theories of plant development upon 

 what is already known of chromosome reduction in this phylum. I have 

 followed during recent years the results of Strasburger, Fol, Beneden, 

 GuiGNARD, Maupas, Flemming and the others but the most impressive 

 fact of all is the insignificance of the data yet obtained in comparison 

 with what should be obtained before engaging in far reaching and re- 



