Electron Micrographs of the Nematocysts of Hydra

Seventeen different kinds of nematocysts have been described and classified by Weill (1930) on the basis of the characteristics of the discharged tube. Only four of these are known to be present on hydras, namely, volvents (desmonemes), streptoline glutinants (holotrichous isorhizas), stereoline glutinants (atrichous isorhizes), and penetrants (stenoteles). The discharged penetrant (fig. 1) consists of the capsule a, butt, which is composed of the shaft b, stylet c, spinneret d, and tube e. In the glutinants the tube is attached directly to the tube, and is either spiny (streptoline glutinant) or smooth (stereoline glutinant). In the resting nematocyst all the component parts are inverted and contained within the capsule

Using Mobile Technologies to Capture the Visitor Experience

Museums give much consideration to how visitors experience their exhibits. Mobile technologies, such as apps on mobile phones and tablets can capture the visitor experience in an automated, on-the-spot manner. Two apps were designed and used to capture visitors’ experiences of interactive exhibits at a science museum. Based on our observations, we discuss (a) the appeal of the technology, (b) the integration of this technology in the overall museum visit and (c) the processing of the collected experience data. Based on our observations, we recommend that museums and science centres critically evaluate the above-mentioned points when considering implementing mobile technologies to capture the visitor experience. Furthermore, we advise institutions to approach mobile technologies as product service systems and take into account the infrastructure that is required to make mobile technologies work.</p