170 BOTANICAL GAZETTE [august 



same at a higher ma 



tion. The general araucarian nature of the specimen is vouched 



ma 



by the alternating and closely compressed tracheary pitting. 



The structure next the pith is elucidated by fig. 4. At the 

 extreme left are the ringed protoxylem and metaxylem elements, 

 which, toward the right, are replaced by those of the secondary 

 wood. In the first pitted tracheid the pits are uniseriate and scat- 

 tered; in the second they are opposite. A careful examination of 

 the wall between the pairs of opposite pits shows that they are 

 separated by white lines. Fig. 5 represents these same elements 

 at a higher magnification, and here the lines are still more conspicu- 

 ous. The study of fossil Pityoxyla, a section of which is shown in 

 fig. 8, has proved that the bars of Sanio in those woods are repre- 

 sented by similar white lines, a condition which would be expected 

 from the cellulose nature of the bars, and the tendency of cellulose 

 structures to disappear in the process of fossilization. That the 

 white lines appearing in figs. 4 and 5 are also bars of Sanio seems 

 unquestionable. The general resemblance of the pitting of this 

 Cretaceous stem to that of the cone axis of Araucaria Bidwillii 

 (fig. 7) is very striking. In the case of the latter, the cellulose 

 composing the bars is still present, and stains a dark blue with 

 hematoxylon, causing the bars to stand out as black lines in the 



photograph. 



ving mai 



primary 



it would be 



Sanio. This possibility may be obviated, as Jeffrey has demon- 

 strated, by using a double stain of hematoxylon and saffranin. The 

 former stains the bars a deep blue and leaves the spirals untouched, 

 while the latter stains the spirals a bright red. With fossil material 

 however, there is no chance for mistake. Here the protoxylem 

 spirals, being lignified, persist, and appear as black lines (left of 

 fig. 4) ; on the other hand, the bars of Sanio, being cellulose, drop 

 out, and appear as white lines (right of fig. 4). 



specimen 



, from 

 may 1 



me with approximately 

 opposite pits. Near the lower limit bars of Sanio may be made out 



