The Biochemistry Set is a useful tool for C3/DS. It is similar to the Biochemistry Kit from Creatures 2. There are four major functions of the Set. It lets you monitor and inject various chemicals in a Creature, including unknownases. The 'Saved list' box will let you create your own cocktails of chemicals to inject or monitor.
After clicking on this button, a list will open up of all the chemicals available in C3/DS, with checkboxes next to them. Click the checkbox to start graphing that chemical. Right-clicking on one box will give the option to graph all chemicals (but this makes the resulting data difficult to interpret!). The "sample rate" is how often the levels of the chemicals will be collected, in seconds. (Note that using fast ticks can give the impression that your creature is metabolising faster than it actually is.) The "time span" is how many seconds will show on the graph at once - the default is 30 seconds, but shorter intervals can make for a clearer graph when the chemicals change very fast.
Each graph will track one creature at a time, although you can have more than one graph open at once. You may choose to graph the selected creature or a random creature, or any other creature. Named creatures will be listed by name in the Biochemistry Set, but unnamed creatures will be listed by their sex and species. Once you've chosen a creature to track, a sample rate, the period of time your graph will show at once and the chemicals you want to track, clicking 'OK' will cause a graph window to appear. Right clicking this graph will give a menu with the options 'inject', 'log', 'clone' (allows you to make a new graph with another creature or different chemicals for comparison), 'properties' (go back to the start and remake your graph options) and 'save window'.
It can export a log of the chemicals in the bloodstream in a CSV format.