292 THE AMERICAN MIDLAND NATURALIST 
not cut out by silt and side refraction of the medium. These 
submerged leaves are, moreover, very thin, and when dried even 
filmy and easily broken and blown away by the slightest gust 
of air. Histologically the cells are more alike and more spherical 
or ovoid in shape. ‘Their vascular tissue is reduced to a minimum 
since scarcely necessary, except the phloem part. The 
floating leaves are produced later and at any one time are fewer 
and smaller, quite thick, in fact miniatures in every way of those 
of the mature plant. Usually not more than two or three are 
found on one plantlet and oftener, but one in small specimens. 
Conard does not emphasize, as might be done, the variation of 
shape of the successive seedling leaves. As already referred to 
he selects aquatic leaves from the sprouting tubers rather than 
from seedlings, and whatever leaf variation in stages are taken 
up (p. 110) are at random picked from different species not serially 
shown as to age or successive appearance. 
Examination of hundreds of seedlings of different ages of 
Nymphala tuberosa showed us that the different leaf forms of this 
one species vary as much if not more than of the tuberous growths. 
Such a series of aquatic leaf variations have been selected as 
typical from the so-called “‘coves” of Bankson Lake, and the 
originals kept in the University herbarium, and- illustrated in 
figures 1-10 plate XIV. The dotted outlines indicate other forms 
from the type connected with them. The order of appearance 
in the growing seedling varies as the breadth of the leaf and the 
size of the basal lobe, the very earliest devoid of blade, the earlier 
narrow and quite devoid of lobes. The second leaf is usually 
narrowly lanceolate or linear (Fig. 1). A curious fact is the presence 
even on the same plantlet of sharp angular sinus at the insertion 
of the petiole (4, 5, 9, 10,) and rounded or even obtuse protrusion 
at place of insertion in these submerged seedling leaves. Fig. 5 
represents that might well be taken for a specimen of the Nuphar 
group, but for the fact that other leaves on the same plant are 
unequivocally those of Nymphaea, and the adhering seed coat 
could not be mistaken. The seeds of Nuphar are large and shiny, 
those of Nymphaea small and black, those of brasenia small 
and grayish white, both of the latter dull. The method of germi- 
nation of Nymphaea seedlings were found to be the same as out- 
lined by Conard.’ 
SMC. Par LO 11 ter 
