EVOLUTION OF ANGIOSPERMS THROUGH APOSPORY I*J1 



duce thousands of spores from a single archegonium, instead of 

 four only, or merely a few. The plants have simply followed the 

 same course as the animals, in extending the periods of family 

 relations. The capsule is the offspring of the moss plant, the 

 prothallus the parent of the fern. The angiosperms add an- 

 other member to the series of prolonged family contacts. The 

 young embryo might be said to be nourished not only by a 

 mother, but also by a grand-mother. The archegoniate plants 

 usually bring only the members or phases of one generation or 

 life-cycle into definite supporting relations, but the aposporous 

 ferns and the flowering plants are able to connect in this way 

 two entirel}'^ distinct generations. Unless apospory takes place, 

 mitapsis concludes each generation with the formation and 

 scattering of separate spores, from which the next generation 

 must be independently built up. But by means of apospory 

 and delayed mitapsis two previously separated generations can 

 be brought into effective contact. It would seem, then, that it 

 is apospory through which the evolution of the angiosperms has 

 become so nearly parallel to that of the mammals that both 

 have actually been described as placentate organisms. 



ORDER OF CHANGES NOT ESSENTIAL. 



It is not necessary to hold that the changes involved in such 

 an evolution of angiosperms from aposporous archegoniates took 

 place in the particular order in which they have been mentioned. 

 There is no objection to supposing that any or all of them might 

 have been in progress during the same period, while the plants 

 were still too small and the tissues still too soft to favor the 

 preservation of fossil remains. The extension of the primary 

 capsule-base or nursing foot into a leafy axis by vegetative 

 growth may have come about after the aposporous seed-produc- 

 ing condition had been reached, rather than before. In Strcf- 

 tocarptis we have plants in which the cotyledons are the only 

 vegetative organs, the plumule consisting only of flower-buds 

 and in Wckuitschta {Tumbod) there are at most but four true 

 leaves. 



If the habit of apospory were adopted far enough back it 

 would have greatly facilitated the other changes, if it did not 



