"Siphonaptera" is the name sometimes given[better source needed] to a short rhyme by the mathematician Augustus De Morgan, from his book A Budget of Paradoxes (1872), Siphonaptera being the biological order to which fleas belong:
De Morgan included the rhyme in a discussion of the possibility that all particles may be made up of clusters of smaller particles, 'and so down, for ever'; and similarly that planets and stars may be particles of some larger universe, 'and so up, for ever'.
- For example: Snyed, JR (2019). "Who watches the watchmen and the problem of recursive flea bites". British Journal of Anaesthesia. Elsevier (published 11 December 2018). 122 (4): 407–408. doi:10.1016/j.bja.2018.11.013. PMC 6435839. PMID 30857594.
- Morgan, Augustus De (1872). A Budget of Paradoxes. Longmans, Green, and Company. p. 377.
- De Morgan, Augustus (1872). A Budget of Paradoxes. Longmans, Green, and Company. pp. 376-377.
- De Morgan, Augustus (1915). Smith, David Eugene (ed.). A Budget of Paradoxes. II (2nd ed.). Editor's note 334.
- Swift, Jonathan (1733). "On Poetry: A Rapsody". Swift's Works. X (1762 ed.). George Faulkner. p. 259. Text from the fascimile reproduction in Elias, AC et al, "The Full Text of Swift's On Poetry: A Rapsody (1733)", Swift Studies, 9 (1994), pp. 17-32.
- Richardson, Lewis Fry (1922). Weather Prediction by Numerical Processes. Boston: Cambridge University Press. p. 66. ISBN 9780511618291.