Systematists should deposit holotypes in the collections of institutions that have a continuous history of employing systematists. Paratypes should be distributed widely to institutions that are able to provide catalogue numbers in exchange. If an institution can't provide catalogue numbers, don't send it any more paratypes, it probably doesn't have the staff to maintain its collections.

Perhaps we can encourage institutions to hire more systematists by depositing paratypes and authoritatively identified material with them, but generally, it works the opposite way. Collections without support staff and active research don't get many visitors or requests for loans, and generally are not thought of when a researcher is distributing material. Collections build up around systematists, wherever they are. Institutions in any country that want to build collections should hire systematists, encourage them to publish and send them to international meetings. Within a generation, from efforts of their staff and from exchange of material with colleagues, they will have substantial collections; in two generations they could join the ranks of institutions with a continuous history for employing systematists.

Of course, it's not quite that simple. For real continuity, you need a series of systematists in the same discipline. My institution, the Academy of Natural Sciences of Philadelphia, has had one or more malacologists on staff continuously since the early 1800's; as a result we have one of the world's largest collections of mollusks, and researchers send us lots of type material. Our collection of crustaceans is just as old, but not nearly as large, because we have not had continuity in that field. Our crustacean collection is not growing, few types are deposited, and loan requests are filled by the collection manager for the mollusk collection.

Gary Rosenberg rosenberg at say.acnatsci.org

"The careful preservation of types therefore, and the interchange of specimens named from types, is of the first importance to save the time and ensure the accuracy of succeeding writers. The Smithsonian Institution has fully recognized this principle by directing that the first available duplicate of all type species described from its collections shall be deposited in some museum open to students on the other side of the Atlantic." --Carpenter 1863 (pp. 339-340)

Carpenter, P. P. 1863. Review of Prof. C. B. Adams's 'Catalogue of the shells of Panama', from the type specimens. Proceedings of the Zoological Society of London, pp. 339-369.