10 IXCHEASE OF THE FOOD SUPPLY Xo. 72 



to the older part of the stem and not to the smaller branches, which are always 

 clothed \vith leaves like those in Fig. -ia. The contrast between the two types of 

 leaves is shown in Fig. 4b, drawn by Mr. Graham from a specimen from White- 

 water Lake. 



The fruiting branch of this form has a very short stalk, and its fruit is the 

 smallest of the three described. The food value of this plant lies in its leaves chiefly. 

 Its ease of propagation makes it very valuable. 



There is a valuable Old Country Pond-weed which has been introduced into 

 our older settled parts and which should be as valuable or even more valuable than 

 the Clasping-leaved form above described. It thrives in the vicinity of Toronto 

 and has been found to be an important food for ducks wintering in the open lake 

 near Toronto. It would, no doubt, do well in the north, and since_it has a very 

 rapid method of propagation by means of buds, would be very easily established. 

 The leaves of this form (Potamogeton crispus) are crinkled and very crisp, like 

 those of the Clasping-leaved form. They are quite long but much narrower than 

 those of the latter. 



The two forms illustrated in Fig. 5, a and b, are Lemnas, and belong to the 

 group of plants known as the Duck-weed family. They are the smallest and simplest 

 of all the flowering plants, one form belonging to the family being not much larger 

 than a pin-head. They thrive on the water of stagnant ponds and on muddy banks. 

 The one illustrated in Fig. 5a is a common form. The plant consists of a single 

 leaf-like roundish disc less than a quarter of an inch in diameter, from the centre 

 of the under surface of which a single root hangs down into the water or penetrates 

 the muddy bank. When fully grown three rather indistinct veins can be seen 

 coming from a point a little behind the centre of the disc. From this spot, too, the 

 root arises, aud, what is more important, from this same spot the new plants 

 spring, and from these again other smaller ones. The parents and offspring remain 

 attached until a little colony of half a dozen or so is formed, and then they 

 separate to form new groups again. They propagate very rapidly by their budding 

 process during the summer. Towards autumn they form little bulblets which sink- 

 to the bottom during the winter and in spring come to the top and start the summer 

 form growing again. The plant also propagates itself by seeds, but these are not 

 either numerous or important. 



The plant represented in Fig. 5b is a submerged form which, though not so 

 important as the other, propagates in thejsame way. The plants when young have 

 a very short connecting thread. This does not. however, remain short, as in the 

 former, but elongates and thickens as well, holding the plants together for con- 

 siderable time, thus producing chains or networks of rather complicated form. 

 Two groups of these are shown in Fig. 5b. The body of the floating form (Fig. 5a) 

 is rather thick and has a large amount of nutriment in it, while the submerged one 

 (Fig. 5b) is much thinner and has much less food material in it. 



GIZZARD ANALYSES 



Towards the end of October Mr. Mickle sent me the gizzard contents of thirty 

 ducks, and from these some important information was obtained. 



In analysing the contents of each gizzard an attempt was made to estimate 

 the proportion of plant and animal food, and then of the various constituents of 

 each. The whole content was put at 10, and the various parts estimated as frac- 

 tions of this. Of course, it is recognized that the individual results are subject to 

 error, but on averaging these the final result is an approximation, and serves to give 



