Nematode Body Structure. The phrase tube-within-a-tube is a convenient way to think of nematode body structure, and also a term used to refer to a major trend in the evolution of triploblastic metazoa (Brusca and Brusca, 1990 Invertebrates).
Neutrals and Universal Colors. Let me explain in details... In general, neutrals include black, white, gray (mix black with white and you've got gray) and different shades of brown. Nowadays a color can be called a neutral based on how effectively it can blend in with other colors. Basically, they match with all colors and color combinations - and don't create much of an emotion.
Colors with a blue or green tint are termed cool, while colors with a red or yellow tint are warm. Grays and white are totally neutral. Neutral colors can be used as background colors for tables and pages. Do not use the color names in your code, because they are non-standard. Use either the HEX or RGB values. Dynamic Color Chart - organized by hue and saturation.