But of course not all the work can be done with eggs or with living specimens of any kind. It is equally important on occasion to examine the tissues of adult specimens, and for this, as a rule, the tissues must first be subjected to some preserving and hardening process preliminary to the cutting of sections for microscopical examination. This is done simply enough in the case of some organisms, but there is a large class of filmy, tenuous, fragile creatures in the sea population of which the jellyfish may be mentioned as familiar examples. Such creatures, when treated in an ordinary way, by dropping them into alcohol, shrivel up, coming to resemble nothing in particular, and ceasing to have any value for the study of normal structures. How to overcome this difficulty was one of the problems attacked from the beginning at the Naples laboratory. The chief part of the practical work of these experiments fell to the share of Signor Lo Bianco. The success that attended his efforts is remarkable. To-day you may see at the laboratory all manner of filmy, diaphanous creatures preserved in alcohol, retaining every jot of their natural contour, and thus offering unexampled opportunities for study _en masse_, or for being sectioned for the microscope. The methods by which this surprising result has been accomplished are naturally different for different creatures; Signor Lo Bianco has written a book telling how it all has been done. Perhaps the most important principle involved with a majority of the more tenuous forms is to stupefy the animal by gradually adding small quantities of a drug, such as chloral, to the water in which the creature is detained. When by this means the animal has been rendered so insensible that it responds very sluggishly to stimuli, it is plunged into a toxic solution, usually formaline, which kills it so suddenly that its muscles in their benumbed state have not time to contract. Any one who has ever tried to preserve a jellyfish, for example, by ordinary methods will recall the sorry result, and be prepared to appreciate Signor Lo Bianco's wonderfully beautiful specimens. Naturalists have come from all over the world to Naples to learn "just how" the miracle is accomplished, for it must be understood that the mere citation of the _modus operandi_ by no means enables the novitiate to apply it successfully at once. In the case of some of the long-drawn-out forms of clustered ascidians and the like, the delicacy of manipulation required to make successful preservations raises the method as practised at Naples almost to the level of a fine art. It is a boon to naturalists everywhere that the institution here is able sometimes to supply other laboratories less favorably situated with duplicates from its wealth of beautifully preserved specimens. METHODS AND RESULTS