212 THE BOTANICAL MAGAZINE. LV oi. xxiv. No. 2S4. 



which of the Abietinae, Araucarimse, and Taxese will represent 

 the oldest type of Coniferas is not easy to decide. 



A word more may be added about the free nucellus of Yezo- 

 strohus. Coulter, in his interesting lecture ' On the Evolu- 

 tionary Tendencies among Gymnosperms (1909),' says ' To 

 select the most primitive type of ovule from among the paleozoic 

 forms that have been investigated is impossible, unless it is 

 assumed that those ovules which are most unlike the modern 

 ones represent the most primitive type. This may or may not 

 be true, but it is the only available criterion'. 



This criterion must remain, under the present state of our 

 knowledge on this subject in the main unchanged, and the free 

 nucellus of a seed may well be considered, as has been done by 

 Robertson, Kershaw, Coulter, and others, as one of the 

 primitive features of a seed. But when the number of seeds 

 with free nucelli among modern plants are largely increased, we 

 see that those seeds in the Paleozoic or in any other horizon 

 which have this feature, become to appear not so much ' unlike 

 the modern ones '; moreover in the light of the facts that even in 

 one and the same genus, the adherence and freedom of nucellus 

 are greatly variable, and also when we remember that the seeds 

 with free nucelli existed in the Paleozoic, side by side with the 

 seeds having adherent type of nucellus and that some species 

 of Pinus and some other Abietinean plants which are considered 

 now as a very old type of Conifersa by Jeffrey, Coulter and 

 other authors, as well as Cycads and Ginkgo which retain in 

 many ways the primitive characters and are rather conservative, 

 do not show the free state of nucellus, we come to the idea that 

 the free state of nucellus may not represent any specially primi- 

 tive type, and both the free and the adherent t} r pes of nucelli 

 arose shortly one after another or simultaneously at the begin- 

 ning when the seed habit has been acquired by the plant in 

 the history of evolution ; and it seems also probable that the 

 fusion or the freedom of nucellus and integument, being of an 

 importance in the ecology of seeds, became partly to be an 

 adaptation character and consequently more or less lost its 

 palingenetic dignity. 



