Absolutely unique desk / dining table - ahead of it's time???  

That's clever little item.
Maybe intended as a desk/ work table? Or a sewing table, so one would cut patterns on expanded table top?
Where are the leaves stored?
Seems kind of unlikely that the two-tone finish was intentional, not just a function of age. I'd guess that the original finish on the outside became cloudy, thus making the wood appear lighter/ faded.

Clever indeed!
thanks for the response. All input is appreciated. It brings to mind the "minimal footprint' tiny homes/apartments that are getting so much press lately. perhaps as an option to the dining table bed combo, etc.

forgot to answer
the leaves have no designated storage area. There are 4 of them, so the table could be extended in increments to accommodate the size of the room or the number of guests.

Had one
i actually picked up one of these desks a few months ago (and sold it shortly after). if i recall correctly, the desk/table was made by saginaw.

I love it.
Sort of the Murphy Bed of desks in a way. It screams '30's-'40's to me. Perfect for the scale of urban studio apartments popular at the time.
I'm seeing two different species of wood, though. Can't imagine why, unless someone decided to bleach/strip it somewhere along the line.

Quite an interesting design!...
Quite an interesting design! It would be absolutely perfect if only the leaves were also somehow stored in the desk. Do you know if this desk was originally designed this way or if it was modified to extend? It's very clever. Somebody should make a contemporary version of this. I'd probably buy one if I didn't have a long built-in desk in my office.

There appears to be room for leaves
between the top of the drawer stack and the bottom of the telescoping table rails.

specifics?
There is no way to hide or attach the leaves (how it is currently designed) when they are not being used. The color/wood change is perplexing. If it had been lightened by sunlight, I would expect more denigration to the finish. If it had been refinished, I would think they they would have at least done the rear of the front legs. The leaves appear to be a different wood altogether. The bottom of the leaves are not veneered and have the color of dark mahogany.
Yet, there is no doubt in my mind that this is how the desk was originally designed.

Watertown Slide Table
The leaves in this table are the original color of the whole unit. The desk portion has been sanded and refinished, maybe even bleached. That's why the offset colors. I have the exact same unit with the four leaves. We are using it today for Christmas dinner, second in two nights, So we bring the leaves up from the basement and Viola a table for 6 hungry people. It is perfect and was built for the days when homes were smaller and had to made functional. It shows us all that homes today have become way too large and that people are not outdoors as much. Instead they are inside on the computer ...LOL.
I have seen these valued at between 200 - 400 dollars. Which I think is way too low. Not sure who actually manufactured the table/desk. The Watertown slide company was one of only 3 major slide manufacturers who provided table manufacturers with just the slide. The wooden slide was discontinued in 1974 and replaced by metal slides for cost effectiveness. Every time we pull this out we are amazed and so my letter today as I told my wife I would look it up on the internet. If anyone does find out who manufactured this piece I would be very interested in knowing.

I just bought one of these today and Nora (the person I purchased it from) gave me this link.  It has a tag on it that I will post in a bit.  It says it was made in Michigan at the Saginaw Furniture Company.  I will check it out further and post.  
 
I would like to know what wood would work best for making the leaves since it doesn't have them anymore?
 
Thanks eveyone!

Can't tell species from here.  I'd guess the "two-tone" finish discussed above is caused by the difference in stain reception between solid wood and veneered surfaces, and sun fading. (edit- upon closer reading, I guess it was sanded)
 
I have seen a similar contemporary credenza in a formal American-colonial style that had leaf storage in the place of the kneehole.  It'll work in a pinch if you're hosting Thanksgiving in a closet or something, it's not hugely practical for general day to day life, but hey...  I would guess that having new leaves made would be prohibitively expensive, but good luck.