I always wondered at how Stan Lee portrayed the webs coming from Spidey’s wrists. Were he to follow the actual spider model, they would come shooting out of somewhere else...
Well, since I was a fan of Spidey back in the 60’s when he was created, I know why.
Spiderman makes the web fluid that dries instantly on contact with air and the applicator spray ejector is part of his costume. They can occasionally be modified to spray other liquids and / or projectiles.........
http://en.wikipedia.org/wiki/Spider-Man%27s_powers_and_equipment