26 ART. 4. — A. YASUDA : ON THE 



In tracing the fibro- vascular bundlles of the mid-ribs from 

 base to apex we find that the first type retains the single bundle 

 to the last ; the second loses the smaller upper bundle on the 

 way, and is reduced to a single bundle ; the third is also reduced 

 to one bundle near the apex, the associated bundles on each side 

 being out of sight ; the fourth loses the uppermost bundle first, 

 then the middle one, the lowest bundle remaining to the end ; in 

 the fifth, the lateral bundles first disappear and then the upper- 

 most l)undle, the lowest one being the survivor; in the sixth the 

 lateral bundles disappear from above downwards till the lowest 

 bundle remains isolated, 



Collenchynia. The position of the collenchyma developed 

 in the mid-ribs varies somewhat according to the above six types : 

 in the first, second, third, fourth, and fifth it is developed only 

 at the upper and lower nmrgins, but in the sixth, liesides the 

 preceding places, collenchyma is also developed on both sides of 

 the mid-ribs. 



GHAPTEB IV. 



THE PETIOLE. 



Contour. The contour of the petioles, as seen in a transverse 

 section, is not of a constant shape in tlie proximal, middle, and 

 distal portions even in one and the same species. Generally 



