Spider Surprise!

A couple of weeks ago I planted some old sweet-pea seeds into some left over potting compost and kept them on a window ledge inside. Only 3 spindly little plants germinated, but the soil must have been hiding a secret sac of spider eggs. Yesterday morning, the pea shoots were covered in a fine lines of silk and clambering about this airy nursery were about a hundred tiny yellow spiderlings. 
Sadly, although they were so miniature and full of charm I felt the sitting room was not their destined home. So, I cruelly cast them out to take their chances in the chilly winds of the outside world.  I did put them in a sunny spot by the sage bush but didn't really think much for their chances. However, this morning some had survived and had clumped together in a tighter ball. Even in this short space of time they had grown somewhat (maybe some cannibalism involved) and a couple of black stripes had developed on their abdomens.  It would be nice to know what sort they were  in case I come across one of them later in the garden.