I found this stitch in Erica Wilson's Embroidery Book at the library (published in 1973 and a good reference book if you can find a copy). It's a compound stitch that uses running stitch as the base and then weaves another color of thread through it. An easy stitch that's perfect for me to cover this week since I'm busy with my houseguests.
So start with a line of running stitch, each stitch the same width and evenly spaced apart. Complete this to whatever length your finished line will be and finish off the end on the back. Rethread your needle with a second color and come up underneath and in the middle of the first stitch.
Weave this thread through the line of stitches, going over and under, without piercing the fabric.
When you come to the end, weave under the final stitch, then turn and come back in the opposite direction.
Go over and under each stitch again, making sure not to pierce the fabric.
When you come back to the beginning take your thread to the back in the same place where it first emerged and finish off.
Here's what it looks like with widely-spaced and smaller, more closely spaced base stitches.
You could use the same color thread for both and have a simple chain but I think it provides more possibilities using two colors.