Just to add to what JC1220 has already said:
Gelatin is used to hold the silver halides on the surface of the substrate (paper in this case) and it is still present in the final print. It has an effect on the process and there is no real substitute, so you can be fairly certain that any light sensitive material using silver halides has gelatin in there as well, no matter what the substrate - even the liquid emulsion you can get is silver gelatin after development.
The silver halides in common photographic use are silver bromide, chloride and iodide - bromine, chlorine and iodine are halogens; bromide, chloride and iodide ions are halides.
There are B&W papers that are not silver gelatin because the silver has been bleached out after a dye has been formed (just like XP-2 B&W film), but these are processed in RA-4 chemicals, not in standard B&W chemicals.
Best,
Helen