THE MICROSCOPE. 61 



PARRIRA BRAVA. 



BY CARRIE L. BARKER. 



r pHE true parrira brava comes form Brazil and Peru. It is a tall 

 1 woody climber with large cordate leaves, very small unfsexual 

 flowers and purplish-black, ovoid, one-seeded, dropacerus fruit, 

 which forms thick bunches resembling grapes in appearance. 



The part found in trade is the long, twisted root or under- 

 ground stem generally cut into pieces from three to six inches long 

 and from one-half to three inches in thickness. Externally it is of 

 a blackish-brown color and is marked with transverse ridges and 

 also with longitudinal wrinkles. 



On making a transverse section we find that it is internally of a 

 light-brown color and has a waxy appearance. We further find that 

 it consists of a central column one-fifth to two-fifths of an inch in 

 diameter — composed of from twelve to twenty converging wedges 

 of wood tissue— and of from three to four concentric zones divided 

 from each other by a wavy, light-colored line. Crossing these zones 

 are wedge-shaped woody rays quite irregularly distributed and 

 separated from each other by rather narrow medullary rays. 



Microscopical Examination. — The part of the plant which I ex- 

 amined was the under-ground stem, it being preferred in trade. I 

 found on making a cross-section of the bark that it consisted of 

 from eight to twelve rows of cork cells. It was impossible, however, 

 to determine the exact number of rows in this layer as the outer 

 bark chipped off and was very irregular. The middle or green 

 layer consisted of oval cells with a few large stone-cells scattered 

 about. The greater part of the stone-cells were in large clusters. 

 The bast or inner layer was rather narrow and composed of ang"ular 

 prosenchyma. The longitudinal section of the bark showed nothing 

 new and was of interest only in that it proved that the large scat- 

 tered masses found in the middle layer were stone-cells and not 

 • long wood tissue. 



A transverse section of the stem showed the large woody 

 bundles composed of angular prosenchyma and with large circular 

 openings scattered about the ends of the vessels. Surrounding 

 these bundles were the medullary rays composed of tabular thin- 

 walled cells. The light-colored line which separated the concentric 



