Abstract: 1. For the preparation of hypnean from Hypnea sp. prior to extraction the algaeshould be treated with Baume' 20°NaOH at room temperature for 2 days, and rinsedwith water. The treated seaweed was then extracted with 15-20 times of its quantityof 0.04% dilute H_2SO₄ solution at 100℃ for 1-1.5hr. After filtration, to the filtrateKCl was added to bring its concentration to 0.2-0.3%, and the solution was allowedto gelatinate. The gelatine was frozen, thawed and dried. 2. The gelatinous strength of hynean was affected by electrolyte markedly. Theorder of effect by cations is:Ca(⁺⁺)K⁺, Cs⁺, Rb⁺Na⁺, Li⁺, NH_4⁺, and by anionsis: Cl^-NO_3_-, SO₄-I_-CO_3_-. 3. The setting point of hynean was affected by KCl, it was increased with increa-se of concentration of KCl. 4. The culturing effects of bacteria (Salmonella typhasa, Pasteure lla pestis,Shigella dysenteriae and Brusella abortus) in bynean media and in agar media werecompared. Hypean gave better results.