[Benandbill]

I thought that would get more hits than 'What's happened to my spuds?' 

Anyway, they've gone soft and the tubers on some are quite large.  Is it still okay to plant do you think?? 

[JayG]

What do you mean by "the tubers on some are quite large?" (If you've managed to grow bigger tubers without actually planting them you could well be on to something!)

Seed potatoes shrink somewhat whilst chitting; perfectly normal and they will be fine when you get them into the soil whatever size they are. 

[peapod]

Ahh...tubers meaning chits? (shoots:- green or white depnding on where they have been?)

Seed spuds can get a little soft dependant on how long you have left them chitting.  
As Jay said, they are shrinking slightly.

If your chits are white and long, then knock them off, they are no good.  You can still plant them.

[Benandbill]

So the knobbly bits are 'chits' and what are tubers?  Leaves?  Thanks for the advice both, I shall plant them today 

[BabbyAnn]

a tuber is the spud itself 

[Benandbill]

You learn something new everyday - thanks BabbyAnn.  I now have them all planted and will hopefully be getting a neat 24 spud plants