The fixation of biological specimens involves the coagulation of cell contents into insoluble substances with the purpose to prevent autolysis and the degradation of tissue. The optimal fixation of biological specimens is achieved on individual live, preferably relaxed, material Bulk fixations usually yield mediocre results as various animal taxa must be fixed by variant means, due to the different chemical makeup of each animal group. A good fixation is generally achieved in a brief amount of time (hours to days) and as soon as the animal is collected. After a favorable fixation is attained, the next procedure is the transfer of the specimen(s) into the proper fluid for archival storage. General biological fixation/preservation procedures are discussed below. Specific fixation and processing for molecular analysis, TEM/SEM, histology, and histochemistry require specialized techniques that are not mentioned in this discussion.