viii] MORPHOLOGY OF BLADDERWORTS 103 



vigorous, they were returned to the sand. By the end of 

 twenty-seven days they had formed turions. These were cut off, 

 and the same alternation of sand culture and nutritive solutions 

 was repeated three times. Each time the effect of the starvation 

 culture was to induce the formation of turions, so that the 

 plant went through the entire vegetative cycle, culminating in 

 'winter' buds, no less than four times between May and the 

 middle of December! The last turions produced were only the 

 size of a pin's head. 



In the preceding pages we have, for convenience, used the 

 terms 'shoot' and 'leaf for descriptive purposes, but it now 

 remains to consider how far current morphological conceptions 

 can be applied to so anomalous a genus as Utricularia. There 

 has probably been more controversy about the morphological 

 nature of the different organs of these plants, than about such 

 problems in the case of any other Angiosperm. It is not pro- 

 posed here to enter into the details of the discussion^ which 

 seems to have been singularly fruitless. In the upshot, the main 

 point, which emerges from a study of the literature, is that in 

 this genus the distinction habitually drawn by botanists be- 

 tween stem and leaf, breaks down completely. The bladder is 

 probably best interpreted as a modification of part of the 

 " leaf 2," but even if this be conceded it does not carry us far, 

 since the nature of the " leaf " itself still stands in dispute. By 

 some authors, the entire vegetative body, apart from the in- 

 florescence axis, has been regarded as a root system, while 

 others view it either as wholly axial or as consisting of stem 

 and leaves. A view which has received considerable promi- 

 nence, is that the entire plant is a much divided leaf^, but if this 

 be so, it must, as Goebel has pointed out, be admitted that this 

 " leaf " possesses many characters which we are accustomed to 



^ For an historical survey of the literature, see Goebel, K. (1891) and 

 Gliick, H. (1906). 



2 Meierhofer, H. (1902). Another interpretation is illustrated in 

 Fig. 72 5, p. 106. 



3 Kamieriski, F. (1877). 



