cucumber seed question

Leave your chosen cucumber on the plant until it is yellow. Take home and slice in half. Scoop out all of the sedds and the jelly like coating. Get a 1 pint jar and half fill with water and place the jelly and seeds in this. Keep an eye on it and when the seeds sink to the bottom strain the lot through a fine sieve.  Rinse thouroughly until you only have the seeds left and place them on kitchen paper to dry. When they are dried place in a airtight container and keep cool and dark until you want to use them. Remember though that F1 plants will not produce the same plant from seed.