A biological reaction apparatus for receiving at least one substrate having a sample located in a sample region, and a separate cover, such that a reaction chamber is formed between the cover and substrate over the sample region, wherein the apparatus includes a locating means to locate the substrate; a cover locating means for locating and moving the cover with respect to the substrate; a fluid dispensing means for dispensing fluid into the reaction chamber; and a draining mechanism; wherein the draining mechanism includes wicking means.