Cactus / new seedlings

As a trial, I sowed cactus seeds in mid of the winter.
This timing allows me to graft seedlings in the very early spring.
Date of sown: 01/07/2013
Seeds: 6 species of Ariocarpus
Heating: Temperature adjustable heating pad
Temperature target: 30 'C on top of potting-mix ( pad setting is 33 'C)
Lighting: natural
It seems the germination has been completed. I will remove pots from the heating pad soon.
The photo is one of pots, Ariocarpus retusus v furfuraceus cv Daruma Seiji.