snail is not firmly attached to the substrate by its foot, it can be blown away by the spray and lost. We have found this to be less of a problem in the field, where attachment to the substrate appears to be better, but it can be a problem in the laboratory. To counteract this we have developed a way of freezing small snails indirectly. The snail is allowed to crawl onto a piece of aluminium foil. It can then be lifted without being disturbed and the spray directed to the underside of the foil. Since the foil is thin and of high thermal conductivity, the snail is again frozen almost instantaneously. We have used this technique most frequently for studying the genital anatomy of snails of the genus Heterostoma. These are small helicids, usually below 7 mm in maximum shell width. Freezing and thawing is extremely rapid and effective. The foot always remains extended and the tentacles are usually only partly retracted. Initially, we found that attempting to withdraw the body of the snail created a vacuum in the shell often resulting in damage to the body. This could be avoided by making a small hole near the protoconch with a mounted needle. Most of the genitalia were almost always removed intact, but the hermaphrodite gland was usually left behind. Also, the digestive tract often remained within the shell and the method would need to be adapted if this part of the anatomy were required. Other than the problem of a small amount of damage to the shell near the protoconch, the main disadvantage with this method is its cost compared to more traditional methods. At the time of writing, a 400-ml can of spray from RS Components costs about £8 (around US $11 or €13). With care, we have found a can of this size can successfully be used on about 150 Heterostoma individuals. Obviously, more spray is needed for larger individuals and so cost would be increased. Costs incurred in the drowning method are negligible. However, where the drowning method is inappropriate or where it is essential to collect samples from the field without disturbance, we have found this method to be an effective alternative, especially in the field where the spray’s portability and ease of use are clear advantages.

中文翻译：

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电器元件冷冻喷雾作为杀螺和备螺方法的应用

蜗牛的脚没有牢固地附着在基材上，它会被喷雾吹走而丢失。我们发现这在现场不是一个问题，在那里对基板的附着似乎更好，但在实验室中可能是一个问题。为了解决这个问题，我们开发了一种间接冷冻小蜗牛的方法。蜗牛被允许爬到一块铝箔上。然后可以在不受干扰的情况下将其提起，并将喷雾引导到箔的下侧。由于箔很薄且具有高导热性，蜗牛几乎立即再次冻结。我们最常使用这种技术来研究异口螺属蜗牛的生殖器解剖结构。这些是小的螺旋体，最大壳宽度通常低于 7 毫米。冷冻和解冻非常快速和有效。脚始终保持伸展，触手通常仅部分缩回。最初，我们发现试图取出蜗牛的身体会在壳中产生真空，这通常会导致身体受损。这可以通过用安装的针在原贝壳附近打一个小孔来避免。大多数生殖器几乎总是完整地移除，但雌雄同体的腺体通常被留下。此外，消化道通常保留在壳内，如果需要这部分解剖结构，则需要调整该方法。除了原壳附近的外壳有少量损坏的问题外，这种方法的主要缺点是与更传统的方法相比成本较高。在撰写本文时，来自 RS Components 的 400 毫升喷雾罐售价约为 8 英镑（约合 11 美元或 13 欧元）。小心翼翼，我们发现这种尺寸的罐头可以成功地用于大约 150 个人。显然，较大的个体需要更多的喷雾，因此成本会增加。溺水法所产生的成本可以忽略不计。然而，在溺水方法不合适或必须在不受干扰的情况下从现场收集样品的情况下，我们发现这种方法是一种有效的替代方法，特别是在喷雾的便携性和易用性具有明显优势的领域。