396 Wisconsin Academy of Sciences, Arts, and Letters, 
Kanunculus. Teleologically speaking, the plants in the deepest 
water should grow the tallest so as to obtain more light for the 
manufacture of food and for the formation of flowers and fruits. 
An “adaptation” to this effect has, however, not been provided by 
Nature. Plants growing 7 or 8 meters below the surface reach 
heights of 1 or 2 meters, those in deeper water still less; while 
those which are but 3 or 4 meters deep frequently reach the sur¬ 
face. These conditions are illustrated in flgures 5 and 6. 
Another interesting point in this connection is that in Green 
Lake many instances were observed of plants flowering before they 
reached the surface, even when they were growing in fairly shallow 
water. In Mendota this was not noticed, and indeed some of the 
larger plants grew 5 or 6 meters to the surface before they flow¬ 
ered. These facts suggest that there is a minimal light intensity 
for the production of flowers, which is of course realized further 
beneath the surface in Green Lake than in Mendota; so that in the 
latter lake some plants remain vegetatively active for a longer 
period and Anally grow to reach the surface, in spite of the re¬ 
tarding effects of low temperature and low light intensity. Dif¬ 
ferent plants probably vary in this respect. The whole argument 
does not, of course, concern such plants as Ceratophyllum, which 
regularly produces flowers under water. 
Literature Cited 
1. Needham, James G., Chancey Juday, Emmeline Moore, Charles K. Sibley, 
and John W. Titcomb. A biological survey of Lake George, N. Y. 
State of New York, Conservation Commission. 1922. 
2. Pearsall, W. H. The aquatic vegetation of the English lakes. Jour. 
Ecol. 8: 163-199. 1920. 
3. Rickett, H. W. A quantitative study of the larger aquatic plants of 
Lake Mendota. Trans. Wis. Acad. Sci., Arts, and Let. 20: 501-527. 
1922. 
Table 1. List of plants collected. 
Submerged plants, forming main plant belt. 
1. Ceratophyllum demersum L. 
2. Chara sp. 
3. Drepanocladus. 
4. Elodea canadensis Michx. 
5. Myriophyllum verticillatum L. var. pectinatum Wallbr. 
6. Naias flexilis (Willd.) Rostk. & Schmidt. 
7. Potamogeton amplifolius Tuckerm. 
8. “ foliosus Raf. 
9. ‘‘ heterophyllus Schreb. 
