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The problem of the origin of corn has intrigued botanists and other students of plants for more than four centuries. The plant was unknown in any part of the Old World before 1492, while in the New World it was the basic food plant of all pre-Columbian advanced cultures and civilizations, including the Inca of South America and the Maya and Aztec of Middle America (1). Although these facts point strongly to its American origin, some writers have continued to argue eloquently for an Old World origin. A living wild form of corn has never been discovered, despite the extensive searches for it which have been carried on in various parts of the hemisphere. The absence of a wild form has been conducive to speculation-sometimes reaching the point of acrimonious debate-about its probable nature. There has, however, been general agreement that modern corn is unique among the major cereals in its grain-bearing inflorescence (the ear), which is completely enclosed in modified leaf sheaths (the husks), the plant being thus rendered incapable of dispersing its seeds. How, then, did wild corn, which to survive in nature must have had a means of dispersal, differ from modern cultivated corn? Where did it grow? How did it evolve under domestication?These are some of the questions that comprise the corn problem.Close collaboration in recent years between archeologists and botanists has furnished at least partial answers to all of these questions, and has also contributed to solving the problem of the beginning of agriculture in America and The authors are, respectively, Fisher professor of natural history, Harvard University, Cambridge, Mass.; director of the Tehuacan Project, Robert S. Peabody Foundation for Archeology, Andover, Mass.; and research fellow, Bussey InstitutiOn, Harvard University. 538 the rise of prehistoric cultures and civilizations. The first substantial contribution of archeology to the solution of the corn problem was the finding of prehistoric vegetal material in Bat Cave in New Mexico, excavated by Herbert Dick, then a graduate student in the Peabody Museum of Harvard University, in two expeditions, in 1948 and 1950. Accumulated trash, garbage, and excrement in this cave contained cobs and other parts of corn at all levels, and these cobs and parts showed a distinct evolutionary sequence from the lower to the upper levels (2). At the bottom of the refuse, which was some 2 meters deep, Dick found tiny cobs, 2 to 3 centimeters long, which were dated by radiocarbon determinations of associated charcoal at about 3600 B.C. Anatomical studies of these cobs led to the conclusion that the early Bat Cave corn was both a popcorn (a type with small, hard kernels capable of exploding when exposed to heat) and a pod form (a type with kernels partly enclosed by floral bracts which botanists call glumes and the layman knows as chaff) (3). Because the Bat Cave corn was both a popcorn and a pod corn, Mangelsdorf undertook to produce a genetic reconstruction of the ancestral form of corn by crossing pod corn and popcorn and ...

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During the summer of 1963 and the spring of 1965, a study was made comparing the subtidal sediment salinities with those of the immediately overlying water in a small estuary north of Woods Hole, the Pocasset River, and relating these findings to the distribution of the estuarine fauna. The estuary is a fluctuating type with a nearly constant river flow. At each location, there are pronounced though precise fluctuations of the water salinity with tidal periodicity. Bottom waters show periods of highly saline, essentially marine water and periods of nearly freshwater, separated by abrupt and brief transitional periods throughout the upper half of the estuary. The low salinity phase is longer at the upper end of the estuary and the high salinity phase gradually predominates as one proceeds seaward. In contrast to the marked fluctuation in bottom salinity, the salinities in the sediments are stable and constant, with each station having its own characteristic salinity that gradually increases from the uppermost reaches to the mouth. This salinity regime has a marked effect on the distribution of the benthic fauna. The epifauna, subjected to the extreme salinity fluctuation and rapid and extreme salinity changes, is poorly represented, particularly in the upper part of the estuary. The infauna, living under much more stable salinity conditions, make up the vast majority of the fauna. The periodic short‐term fluctuations in the water salinity stabilize the sediment salinities and subject the infauna to less physiological stress than that imposed on the epifauna. A brackish water fauna dominates the uppermost part of the estuary. The fauna is transitional in a zone where the sediment salinities vary from 19 to 22%. At higher sediment salinity values, lower in the estuary, the marine element predominates. Animals collected from the transitional zone were exposed in the laboratory to low and high salinity water obtained from the same locality at low and high tide, respectively, and to a control salinity duplicating the average sediment salinity of the zone. There were four patterns of response: 1) stress symptoms and death usually in less than 24 hr; 2) stress symptoms and recovery; 3) behavioral response; and 4) normal, identical activity in the low, high, and control salinity water. These responses were related to the depth distribution patterns of the species, sediment salinities, and redox potential values at the collecting site.

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Potassium enrichments in marine sediments have been reported which would imply a rate of diffusion of potassium into the oceans much larger than any of the know rates of addition or removal by other mechanisms. Experiments with mixtures of seawater and clay suggest that spurious enrichments can be produced if sediment samples are allowed to warm up before the pore water is expressed.

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