This apparatus involves an assembly of a test tube and paddle insert. The tube has a frustoconical body and a tapered tip in which is a well, having opposed tapered wide flat walls and narrow walls. The paddle insert has a long handle integral with a transparent tapered paddle head that is shorter than...http://www.google.fr/patents/US4528187?utm_source=gb-gplus-shareBrevet US4528187 - Apparatus for collecting and microscopically examining a specimen
Apparatus for collecting and microscopically examining a specimen
