CHAP. XVII. DEVELOPMENT OF THE BLADDERS. 427 



margins of the rest of the leaf. But strong objections 

 may be urged against this view, for we must in this 

 case suppose that the valve and collar are developed 

 asymmetrically from the sides of the apex and pro- 

 minence. Moreover, the bundles of vascular tissue 

 have to be formed in lines quite irrespective of the 

 original form of the leaf. Until gradations can be 

 shown to exist between this the earliest state and a 

 young yet perfect bladder, the case must be left 

 doubtful. 



As the quadrifid and bifid processes offer one of the 

 greatest peculiarities in the genus, I carefully observed 

 their development in Utricularia neglecta. In bladders 

 about T-i-o of an inch in diameter, the inner surface 

 is studded with papillae, rising from small cells at the 

 junctions of the larger ones. These papillae consist of 

 a delicate conical protuberance, which narrows into 

 a very short footstalk, surmounted by two minute 

 cells. They thus occupy the same relative position, 

 and closely resemble, except in being smaller and 

 rather more prominent, the papillae on the outside of 

 the bladders, and on the surfaces of the leaves. The 

 two terminal cells of the papillae first become much 

 elongated in a line parallel to the inner surface of the 

 bladder. Next, each is divided by a longitudinal 

 partition. Soon the two half-cells thus formed sepa- 

 rate from one another ; and we now have four cells or 

 an incipient quadrifid process. As there is not space 

 for the two new cells to increase in breadth in their 

 original plane, the one slides partly under the other. 

 Their manner of growth now changes, and their outer 

 sides, instead of their apices, continue to grow. The 

 two lower cells, which have slid partly beneath the two 

 upper ones, form the longer and more upright pair of 

 processes ; whilst the two upper cells form the shorter 



