Hypothetical types of biochemistry in the late 1960s, these machines are often classed as computers (or computer-guided robots) and filed under "silicon-based life", even though the silicon backing matrix of these processors is not nearly as fundamental to their operation as carbon is for "wet life". Arsenic, which is chemically similar to phosphorus, while poisonous for most life forms on Earth, is incorporated into the biochemistry of some organisms. Some marine algae incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines. Fungi and bacteria can produce volatile methylated arsenic compounds. Arsenate reduction and arsenite oxidation have been observed in microbes ("Chrysiogenes arsenatis").
John Lightfoot (biologist) "Ryssus", but including also "Lichen" as "Algae Terrestres", terrestrial algae. Only nine genera of fungi are recognised in the book: "Agaricus", "Boletus", "Hydnum", "Phallus", "Helvella", "Peziza", "Clavaria", "Lycoperdon", and "Mucor" (listed on page 645); a tenth fungal genus, "Tremella" is covered, but included among his algae. "Scottish Fungi" note that "While his classification might be a bit wonky by today's understanding, most of the species he recorded can be traced to modern taxa", and that he provided the first British records for the chanterelle and the summer truffle. The book has an "English and Scotch Index of the Names of