176 Prof. Mohl oi the Import of the 



in size, and a more or less perfect metamorphosis into the form of a 

 vegetative leaf. Generally, and especially upwards from the second 

 flower, this metamorphosis into a leaf provided with sheath, ligula 

 and lamina is perfect (fig. 4jo", fig. 5y); while even when the 

 lowermost flower is partially abnormal, its inferior palea (fig. 4 jo', 

 fig. 5y) frequently forms an intermediate stage between the nor- 

 mal form and that of a vegetative leaf. The latter cases are na- 

 turally best suited for allowing us to obtain an insight into the 

 manner in which the metamorphosis of the palea into the vege- 

 tative leaf takes place. It is seen by the comparison of several 

 such intermediate stages that the normal palea does not solely 

 correspond, as we might at first be inclined to admit, to the 

 sheath of the vegetative leaf, and that the metamorphosis of the 

 palea into a leaf does not consist in a budding forth of the lamina 

 from the apex of the palea, but that a separation of the various 

 parts of the palea, which are intimately fused together, takes 

 place, and a dismemberment of them one from the other re- 

 sults. The normal palea possesses five nerves, of which the central 

 one extends to the apex of the palea, while the lateral nerves are 

 lost within the transparent scarious membrane. On its meta- 

 morphosis into a leaf the palea becomes elongated ; its inferior 

 portion surrounds the superiorly-situated portion of the spicula 

 in the form of a vagina, while its upper portion bends more or 

 less outwards and becomes changed into the lamina of the leaf 

 (PI. XIII. B, fig. I, fig. 2 to 5y). In those palese in which this 

 metamorphosis is merely indicated, the palea still retains nearly 

 its proper form and the reddish colour which is difiiised over the 

 normal palea, and it is only its apex which has become thicker, 

 of a greenish colour, uncinate and recurved superiorly (fig. 4 jo', 

 fig. 5jE)') : a separation into vagina, ligula and lamina is not yet 

 indicated. When the metamorphosis has advanced further, the 

 whole palea is lengthened considerably, its upper portion has be- 

 come thicker, green and leaf-like, while the lower portion has re- 

 tained its more delicate texture, transparency, and likewise fre- 

 quently the reddish colouring ; the nerves, which are still present 

 to the number of five, have acquired a more parallel position in 

 consequence of the elongation of the leaf, and become confluent 

 towards the uncinately- curved apex of the latter. The margin is 

 scarious as in the normal palese. The separation into the various 

 parts of the vegetative leaf now begins, and is terminated by the 

 development of the ligula and the transverse separation between 

 the upper green and the lower brighter-coloured parts of the 

 palea. 



The formation of ligula frequently occurs only at one part of 

 the leaf, in its central line, or on one of the lateral halves, or on a 

 part of one of these, while in the other portion lamina and vagina 



