No. 544] BOTANICAL SOCIETY OF AMERICA 233 



was found that here the leaf-traces were ephemeral in 

 their persistence, exactly as in the older Mesozoic repre- 

 sentatives of the Araucarian stock from the Lower Cre- 

 taceous, Jurassic and Triassic deposits. Here appears 

 a very striking example of the validity of the law of re- 

 capitulation as exemplified by the young individual, the 

 seedling stem for a short part of its vertical length re- 

 peating ancestral conditions which have long disap- 

 peared in the adult. Let us consider two remaining 

 characters together, in order -to economize time. The 

 water pores of the tracheids in existing Araucarian con- 

 ifers occur in a crowded and alternating condition and 

 are deformed or flattened by mutual contact, a feature 

 of resemblance to the oldest known gymnosperms. This 

 feature is in marked contrast to the pit arrangements of 

 the other existing tribes of conifers, where the water 

 pores are loosely grouped and when numerous and mul- 

 tiseriate are opposite. Another unusual feature of the 

 wood of existing Araucariineae is the absence of wood 

 parenchyma, a feature likewise illustrated by the woods 

 of the Paleozoic gymnosperms. If we follow the Arau- 

 carian conifers below the horizon of the present, we ob- 

 serve in the older representatives a condition of pitting 

 of the tracheids, which the lower we go geolc.gi.-nlly, 

 becomes more and more like that found in the other tribes 

 of conifers, particularly the Abietineae, so much so that 

 Gothan, who has recently described the Jurassic woods 

 of Spitzbergen and other arctic islands, which in the 

 Mesozoic supported a luxuriant flora, has identified them 

 as of Abietineous affinities. It is further found in the 

 case of those Mesozoic fossil woods which most nearly 

 resemble the living genera AgatUs and Araucaria, that 

 wood parenchyma was exceedingly abundant. Now let 

 us examine our Araucarian seedlings in regard to these 

 features. The wood of the cotyledonary region here ex- 

 emplifies both the characteristic pitting and presence of 

 wood parenchyma of the Mesozoic Araucanoxylon type. 

 Thus the Araucariinea?, which we are able to follow very 



