VOLUME LXVII NUMBER 6 



THE 



Botanical Gazette 



JUNE igig 



structure, development, and distribution 

 of so-called rims or bars of sanio 



Irving W. Bailey 



(with plates xiii-xv) 



Introduction 



In recent years a number of botanists and paleobotanists have 

 given considerable attention to the study of the distribution of 

 certain bandhke thickenings of the middle lamella, so-called rims 

 or bars of Sanio, in the g}innosperms, and their significance in 

 discussion concerning the relative antiquity of the Abieteae and 

 Araucarieae.^ Before considering the distribution of these bandlike 

 thickenings of the middle lamella, it is desirable to outline the 

 conclusions of various investigators concerning their structure and 

 development. The work of Sanio is particularly significant in 

 this connection, as it is also in a discussion of the controversy 

 that has arisen in regard to the true meaning of the term "bars 

 of Sanio." 



Historical 



Structure and development of Sanio's Querleisten. — It 

 was stated by Sanio (13), in his comprehensive paper upon the 

 anatomy of Piniis silvestris Linn., that in the cambium of young 

 stems the radial and tangential partitions separating adjacent 

 protoplasts are of equal or nearly equal thickness, but in that of 



' The terminology of Engler and Gilg (2) is used in this paper. 



449 



