These, then, are some of the material conditions that have contributed to make the results of the scientific investigations at the Naples laboratory notable. But of course, even with a superabundance of material, discoveries do not make themselves. "Who uses this material?" is, after all, the vital question. And in this regard the laboratory at Naples presents, for any one who gets at its heart, so to speak, an ensemble that is distinctive enough; for the men who work in the light and airy rooms of the laboratory proper have come for the purpose from all corners of the civilized globe, and not a few of them are men of the highest distinction in their various lines of biological science. A large proportion are professors in colleges and universities of their various countries; and for the rest there is scarcely one who is not in some sense master of the biological craft. For it must be understood that this laboratory at Naples is not intended as a training-school for the apprentice. It offers in the widest sense a university course in biology, and that alone. There is no instructor here who shows the new-comer how to use the microscope, how to utilize the material, how to go about the business of discovery. The worker who comes to Naples is supposed to have learned all these things long before. He is merely asked, then, what class of material he desires, and, this being furnished him, he is permitted to go his own way unmolested. He may work much or little, or not at all; he may make epochal discoveries or no discoveries of any sort, and it will be all one to the management. No one will ask him, in any event, what he has done or why he has not done otherwise. In a word, the worker in the laboratory here, while being supplied with opportunities for study such as he could hardly find elsewhere, retains all the freedom of his own private laboratory.