1. Occurrence.--Lemnaceae may occur in stagnant or sluggish streaming waters, specially in ditches, pools, streamlets, inundated rice-fields, etc. They are also found in all other waters in which larger swamp plants offer anchorage to the tiny Lemnaceae. They can be expected between stands of sedges, grasses, cat’s-tail, etc. or between or under swimming water plants, for example Azolla, Eichhornia, waterlilies, etc. The smallest Lemnaceae, consisting merely of a rootless globule, Wolffia, which is always submerged, is easily escaping attention under other water plants. 2. Collecting.--Lemnaceae are mostly found in sufficient quantity and can easily be collected in a bottle or plastic bag. In case they are sparse and small (Wolffia) the use of a wire—netting (old coffee sieve) may be handy. They are kept wet in the bottle or plastic. If they should be kept for several days or longer they should be stored in an open container with a small amount of earth added; the container should be kept in the shade.