Box.— Vol. I.] CAMPBELL— NAI AS AND ZANNICHELLLA. 1 3 



(fio-. 8), and this enlargement quickly assumes the form of 

 a ridge running round it and growing up about the apex in 

 the form of a cup-shaped envelope. A longitudinal section 

 of the young male flower at this stage shows a structure 

 very similar, as might be expected, to that of a vegetative 

 shoot. A definite epidermis covers the apex, and the inner 

 tissues show a separation into plerome and periblem, al- 

 though not quite so definite as in the vegetative apex. There 

 is next to be seen a second envelope growing up, separated 

 from the first by a short interval and remaining closely applied 

 to the body of the stamen, which latter is formed from the 

 whole of the terminal part of the flower; i. e., the apex of 

 the floral shoot is transformed directly into the anther. The 

 resemblance to the young ovule invested with its single in- 

 tegument is very striking, and it is difficult to see why this 

 inner envelope of the stamen should not be considered to 

 be the homologue of an ovular integument. At this stage 

 there can usually be made out a pretty definite central row 

 of cells (fig. 9), corresponding to the plerome of the vegeta- 

 tive shoot, and from which, alone, the sporogenous tissue 

 arises. The outer envelope grows more rapidly than the 

 inner one and soon extends far beyond the apex of the an- 

 ther. It consists throughout of two layers of cells. Whether 

 this envelope is to be regarded as a perianth, or whether it 

 is the homologue of the carpel, or finally whether it is to be 

 considered merely as a bract, it is difficult to say. Its abso- 

 lute similarity in origin to the outer envelope of the female 

 flower is perfectly obvious, and Magnus (1870, p. 38) tries 

 to solve the question by denying that this envelope in the 

 female flower is really of carpellary nature, but states that 

 it is rather of the nature of a bract or rudimentary perianth, 

 comparable, perhaps, to the envelope about the pistillate 

 flower of Zannichellia. 



At the time when the archesporium is first recognizable, the 

 anther (fig. 12) shows an epidermis, below which are two 

 rows of cells surrounding the plerome cylinder. It is the 

 upper cells of the latter which constitute the archesporium, 

 but its exact limits are not easily determined. It is pretty 



