DOMESTICATED PLANTS BLAYDES 321 



hemispheres independently learned to make textiles from the cotton 

 fibers and domesticated the plants more or less simultaneously. 



Variability in dimensions and weight of seeds may add to our ap- 

 preciation of this plant organ. In various acid soil areas in Ohio, a 

 native orchid, known as the rattlesnake plantain {Goody era inibescens 

 ( Willd.) R. Br.) , may be found. The seeds (pi. 4, fig. 16) of this plant 

 are among the smallest known. The dimensions of this magnified 

 specimen are approximately 0.02 inch long by 0.003 inch wide (641.4 X 

 95.3 microns) . The weight is about .000002 gram. Many other or- 

 chids have seeds with dimensions and weight in about this category. 

 In addition, one of the tropical orchids is known to bear about a million 

 seeds to a flower or fruit. 



The natives of the Seychelles Islands in the Indian Ocean and 

 Oriental lands bordering this body of water are accustomed to finding 

 a somewhat monstrous object (pi. 4, fig. 15) washed up on the beaches. 

 For centuries it was thought to be a product of the ocean and was 

 called coco de mei\ with many legends and superstitions developing 

 about it. The hollowed-out shell was highly valued by potentates of 

 the Orient as containers for drinking water. The shell was believed 

 to contain an antidote to any poison that might have been added to 

 the water. In the early part of the nineteenth century the fan palm 

 {Lodoicea sechellarum) was discovered growing on Praslin Island. 

 The nut, or stone, and seed are ordinarily two-lobed, appearing as 

 though two large coconuts had partially joined, and are now com- 

 monly called the double coconut. Occasionally a three-lobed stone is 

 found, which has led to the fallacy that a single fruit may bear from 

 two to three seeds. There is but one seed to a fruit, which is usually 

 two-lobed, about 13 inches wide and 12 inches long with a weight of 

 about 40 pounds — the largest seed known. 



If we were asked to pick out the plant family which is of greatest 

 importance to man and other mammals, it undoubtedly would be the 

 grasses (Graminaceae). There are over 10,000 species of grasses 

 known, having a worldwide distribution, from aquatic to desert habi- 

 tats and from the Tropics to the Arctic. The grains of grasses are, 

 botanically, fruits — fruits with a single seed, which adheres to the 

 membranous fruit coat or pericarp. The illustration on plate 4, 

 figure 18, is a microscopic longitudinal section of a corn grain. The 

 fruit coat is evident as a thin tissue surrounding the relatively large 

 seed. The embryo is in the lower part of the grain, and the remaining 

 krge mass of tissue is the endosperm. This tissue is unique in that 

 it develops ordinarily from the fusion of three nuclei, a male gamete 

 and two nuclei of the embryo sac which are identical genetically to the 

 egg or female gamete. Since these three nuclei are each haploid, the 



