l886.J NEW-YORK MICROSCOPICAL SOCIETY. 13 



form the walls of the spiral ducts or to have a peculiarly inti- 

 mate relation to these walls. These fibres of the Banana polarize 

 well. 



OBSERVATIONS ON THE STRUCTURE OF 

 CASTANEA VULGARIS. 



BY P. H. DUDLEY, C.E. 



{Read April 2d, 1886.) 



The tissues of Castanea vulgaris, var. Americana, A. DC, our 

 chestnut, consist of vessels or ducts, tracheides, parenchyma, 

 and libriform and septate fibres, which are so combined as to 

 present a very complex structure in the fibro-vascular bundle or 

 annual ring. The large vessels form during the first part of the 

 season's growth, and are confined to from one-sixth to one- 

 third of the ring, making two, three, or four quite definite, con- 

 centric rows. 



In transverse sections, each vessel or duct is oval, the major 

 axis being radial to the tree. In size they have large limits of 

 variation in different trees. I find the major axis to range from 

 200 to 500 yt/, and the minor axis from i8o to 410 n. 



These large vessels or ducts are jointed in lengths of from 

 one to two diameters. After the third or fourth year they are 

 filled with tissue which has been designated as Tyloses, and the 

 impression has been conveyed that it is merely accidental. This 

 view I do not accept. In the duramen these vessels or ducts, 

 in this wood, are never empty or open, but are filled with tissue 

 which at one period contained protoplasm. 



Surrounding these large vessels or ducts are cells of little 

 more than parenchyma, though they are lignified according to 

 the indications given by either of the reagents Phloroglucin or 

 Indol. These cells, which Sanio might call intermediate fibres, 

 have septa, and in autumn and winter contain starch. The thin 

 places in their walls are elliptical in some instances, and in 

 others, round. The thin places in the walls of the vessels cor- 

 respond to those of the adjacent tissues except those of the 

 medullary rays, a modification in each taking place, and instead 

 of being elliptical horizontally, they are often so vertically, and in 

 many cases they are triangular in form. In the ring not occupied 



