Dear Michael,
you could find the Enders's paper here:
http://www.archive.org/details/journalofmorphol20wist
Best wishes
Gabriele
Dr Gabriele Conti PhD
Electron Microscopy Laboratory
Department of Cytomorphology
University of Cagliari
Cittadella Universitaria
I-09042 Monserrato (CA)
Italy
Tel: 39 070 6754024
Fax: 39 070 6754003