Hi Kevin, A few responses to your responses. Yes, ethanol is generally a better storage solution than isopropanol. However, in practice it is usually not used, mainly for the reason you mentioned - expense. Not only is pure ethanol heavily taxed, but in many states it is unattainable in quantity without a medical or research license, because it is drinkable. Therefore, isopropanol seems to be the most readily available, most economical, and most generally suitable substitute for long-term storage of most specimens. I'm surprised that your institution uses 40% isopropanol. I suppose 40% might be adequate for maintainence if the specimens were formalin fixed first. The institutional collections I have had contact with (not specifically molluscan, but general zoological or anatomical) have always used 70% isopropyl. I would be concerned that some microorganisms, especially some fungi, might be able to propagate in a 40% solution. Also, water-soluble substances like carbohydrates, glycogen, etc. would not be stabilized in 40% alcohol. They would leach out of the tissue over time. Of course, if the specimen is just for museum display, that wouldn't really matter. Still, dehydration and protein denaturation are the means by which alcohol preserves, and I'd be nervous about a 40% solution providing a sufficient degree of either effect. But, can't argue with success - if it works, that's the best evidence. You also mentioned that 70% isopropanol causes specimens to shrink. That is certainly true if you place the fresh specimen directly into alcohol. The shrinkage is due to rapid extraction of water from the tissues, causing the fragile cell membranes to collapse. However, specimens pre-fixed in formalin won't shrink noticeably in 70% alcohol because the formalin makes the cell membranes and other tissue structures rigid. I was unclear in my comments about EM (electron microscopy). Ordinary histological fixatives are often acceptable for SEM (scanning EM), which examines external structures at relatively low magnification. It is for TEM (transmission EM), looking at cellular untrastructure at high magnifications, that specialized fixatives are a must. Regards, Paul M.