Two months later and one of the two biggest dorotheae has grown completely out of his seed leaves. The seed leaves are no longer visible and I didn't even help. They dried out all by themselves.
This big one is also quite stable now... no more shrinking horribly and then almost exploding when being watered. This gives me hope!
The second one, however, will take some more time... It shows almost no change.
Dorotheae seedlings on May 13, 2008