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.
Examples of complements are red and green, blue and orange, and yellow and violet. Term. neutral. Definition. Neutral colors are created by combining even amounts of complements to create muddy earthy tones. In clothing a neutral is grey and khaki. In paint it is more muddy shades of brown.