■ 

























L 









u 







































. 







ANATOMY, AND LIFE-HISTORY OP THE CONlFERiE. 307 



the lower portion, which latter represents therefore a leaf or bract 

 within the same cellular sheath as the fruit-scale proper. 



In the genus Agathis (syn. Dammara) the condition of things 

 is much as it is in Cunninghamia ; the bracts are in spiral sequence 

 with the leaves, a few intermediate structures being found at the 

 base of the cone. The fruit-scale is not visible externally, the 

 seeds springing, or appearing to spring, direct from the inner 

 surface of the bract. The seed of Agathis is provided with one 

 wing (or sometimes two), and this wing, according to Dickson, is 

 on the right side if the direction of the bracts be dextrorse, to 

 the left if the cone-scales be sinistrorse. This observer has traced 

 the development of the inverted ovule of Dammara from the base 

 of the bract, so that in Agathis we have the same condition as in 

 tallitris. Dickson * considers that there is concrescence betweeu 

 the bract and the peduncle of the flower (ovule). In support of 

 this he shows a double vascular bundle, one division going to the 

 bract, the other to the ovule, but this latter may belong to the 

 seed-scale and be, in fact, its only representative. Eichler, how- 

 ever, figures the bundle which proceeds to the ovule as springing 

 from that proceeding to the bract. Van Tieghemt figures a 

 double vascular system in the bracts of Agathis {Dammara), the 

 upper series belonging to the seed being completely concealed 

 within the same epiderm and parenchyma as that which surrounds 

 the vascular system of the bracts. 



In Araucaria the bracts are continuous with the leaves, as in 

 Agathis, and are congenitally adherent to, or inseparate from, the 

 fruit-scale, which latter, in the mature cone, largely exceeds the 

 bract, just the opposite of what happens in Agathis. Brongniart 

 and Gris J review the different opinions that have been held as to 

 the simple or compound nature of tbe scale, and sum up by 

 expressing their assent to the views put forth by Dickson and 

 van Tieghem as to its double nature, as revealed by the 

 arrangement of the vascular bundles, which is essentially that of 

 other Coniferae, although the bundles for the bract and for the 



seed-scale remain invested by one undivided sheath of cellular 

 tissue. 



In Sciadopitys the bracts are iu continuous sequence with the 



* Dickaon, Bot. Soc. Edinb. July 1 1, 1861 . 



t Van Tieghera, Anatomie de la fleur dea Gymnospermes, tab. 15. figs. 74-76. 

 t Bull. Soc. Bot. France, vol. xviii. (1871), p. 135 ; Dickson, Bot. Soc. Edinb. 

 «« ; Van Tieghem, I. c. p. 277. 



I 



















■ 





■ 



: 





- 



■ ■ 



. ■ 





