A Universal Molecule of Living Matter
The tetrapyrrole ring, a chemical structure made up of four smaller rings, occurs in the chlorophyll of plants, the hemoglobin of blood and many enzymes which, like hemoglobin, take part in respiration
Discoveries in Nitrogen Fixation
Until recently only a few microorganisms were thought to fix the nitrogen of the atmosphere in the form essential to higher plant and animal life. Now a number of others have been found
Tracers
The relatively recent application of labeled atoms in biological research has already brought out some remarkable information about the chemistry of life