The Bill of Fare 69 



Because of its extent, the variety of small animals, and the 

 many kinds of living places it provides for them, the area 

 about the underwater plants probably harbors the greatest 

 concentrations of animal life in the marsh. Different small 

 species occupy the diverse water depths. I found some swim- 

 ming on or near the surface, some attached to, or creeping 

 on, the stems, and with a small net I could scoop up many 

 which crawled in the sand or mud, or buried themselves in 

 the ooze of the bottom. I occasionally spaded up and ex- 

 amined material from the shallows. When the surface was 

 still, I could look down in the water on the shady side of the 

 boat and watch the living things moving about— small fish, 

 crustaceans, and the like. I often saw mussels on the bottom 

 and shells which had been emptied by the muskrats, and now 

 and then a turtle would scramble off a log. I knew that the 

 water abounded with animals of miscroscopic size, such as 

 protozoans and crustaceans, which ate the diatoms. Many 

 other creatures helped to make up the invisible population 

 always present in water. A friend, an expert on limnology, or 

 fresh-water life, allowed me to look through his microscope 

 at many of the diatoms. They were enclosed in silica cases 

 of a design daintier and a beauty more exquisite than the 

 vanity cases of wealthy women. Seeing them I could under- 

 stand why men have spent entire lifetimes in the microscopi- 

 cal study of marsh and lake life, a study so complex and 

 involved that its details are quite beyond the reach of any- 

 body but the specialists. 



My trips through the marsh taught me something about 

 the regularity of its wildlife. I became acquainted with the 

 various nesting spots of the bitterns and knew that these 

 locations were occupied each year by the same or other 

 bitterns. I knew that the Virginia rails preferred certain dense 

 cattail localities. The cliff swallows returned each year to nest 

 in the only local substitute for cliffs— the walls of some of the 

 University buildings. The green heron worked up and down 



