:l\:l DEVELOPMENT OF 



Bheath, and becoming elongated, especially towards autumn, if the 



"round is moist. The two lower sheaths of the bud perish, and 

 by September scarcely any traces of them are visible, so that the 

 sheath which is perforated by the roots, which was at first the 

 third, is now the first, and that in whose axil the bud of the 

 second succeeding year is seated is now the second. 



This bud is now enlarged and somewhat changed. The annular 

 appendage of spring is in autumn closed with the exception of 

 a minute orifice, whose margins at a later period wrap over each 

 other ; other appendages are inclosed within this. The swelling 

 which was visible in spring at the lower side of the bud is now 

 much larger, and the young pseudo-tuber is visible within. It has 

 thrust aside the lower or frontal side of the base of the first leaf 

 of the bud from the portion of the stem of the mother bud, to 

 which it was originally closely attached all round, while the upper 

 or dorsal side of the base of the first leaf remains attached to the 

 corresponding portion of the stem. The bud then rests on the 

 top of the infant pseudo-tuber. 



In order to display clearly the relation of the infant pseudo- 

 tuber to its bud and to the leaf in whose axil the bud is seated, it 

 is necessary to make a vertical section through the medial line 

 of that leaf and through the whole of the parent bud. The tuber 

 is not formed in the axil of the penultimate sheath of the parent 

 bulb in such a way as to stand absolutely above the point of 

 insertion of the sheath, and to be closely inclosed by it with its 

 upper surface only ; on the contrary, the leaf seems for a short 

 space at the very base, which is rather thick, to be' split into two 

 plates at the point where the tuber is seated, and only at that 

 point. The lower and thicker layer (o) invests now the lower and 

 lateral surface of the tuber, and has normally its insertion on the 

 corresponding point of the axis of the parent bud ; the upper 

 layer (n), which is very thin and runs for a short distance only, 

 is inserted on the young tuber itself, and close beneath the point 

 of insertion of the first leaf of the infant bud, seated on the crown 

 of the infant tuber, so that the point of insertion of this upper 

 layer, that of the penultimate sheath of the parent bud, and that of 

 the first of the infant are parallel to each other, and scarcely take 

 up a quarter of a line. In this fissure or cavity, which has no 

 cuticle, the bulb is completely inclosed. This is the normal 

 construction, but sometimes the two surfaces of the parent 

 leaf are not separated in this way, but remain continuous. In 

 this case, a thin membrane, inserted a little below the point 



