JEFFREY. — ARAUCARIOXYLON TYPE. 559 



found, in those spocirs of Araucarla, wliicli liavr both the upi)er 

 and lower systems of fibrovascnhir hundli's present in the e()ne-.scules 

 of tlioir o\ uhite strohihis, that the axial re},non of the cone does not 

 show certain remarkable features found in the case of those species 

 in which the upper system of cone-scale bundles has disappeared. In 

 the latter condition there are apparent medullary resin-canals present 

 in the pith of the cone axis. In the lower region of the cone these 

 resin-canals are often surrountlcd with the tissues of the xylem, which 

 constitute medullary strands joining with the wood of the cylinder 

 of the axis, at the points where the supply of the cone-scales is given 

 off. Without going into the matter here it may be stated that the 

 medidlary strands, containing resin canals in certain species of Arau- 

 caria and Agathis represent the vanished upper system of cone-scale 

 bundles. The wooden envelope of the resin-canals disappears in the 

 upper region of the cone and is best developed in the peduncular region. 

 In Agathis, only the most primitive species have the medullary vas- 

 cular strands. In the case of Agathis BidwiUu, resin-canals are found 

 not only in the wood of the medullary system of bundles but they 

 likewise not unfrequently make their appearance in the bundles of 

 the lower cone-scale series, which are alone present in this genus. 

 This feature is shown in Figure/, Plate 7, which represents a cone-scale 

 supply in the lower region of the cone, passing out through the wood 

 of the axis. In the upper region of the scale supply and immersed 

 in the elements of the primary xylem, is to be seen a dark mass w'hich 

 represents a resin canal filled with mucilaginous contents, a common 

 accompaniment of the resinous secretion both in Agathis and Arau- 

 caria, as well as in the resin passages of extinct representatives of the 

 Araucarian stock. Mucilage is particularly abundant with the resin 

 in the canals of Agathis. The peculiar position of the resin canal in 

 the primary wood, is to be compared with the conditions in li\'ing 

 and extinct pines, where the first formed resin canals are often em- 

 bedded in the elements of the primary wood. The present writer 

 has described similar conditions in the case of the vestigial resin-canals 

 of the cone-axis and cone-scales of the genus Sequoia. ^^ Interesting 

 in this connection are likewise the resin canals in the primary wood of 

 the root in the two subtribes of the Abietineae, the Pincae and the 

 Abieteae. The occurrence of resin canals in the outgoing \ascular 

 supply of the cone-scales on Agathis Bidivillii is an extremely incon- 



39 Jeffrey, Comparative Anatomy of the Coniferales. I. The genus Sequoia, 

 Mem. Boston Soc. Nat. Hist. 5. 



