Tom Johnson, excellent furniture repairer and refinisher, who is on
Youtube, recommends "Old Brown Glue". It is a brand of premixed stabilized
hide glue. He usually heats it up some before using. He uses a syringe to
apply it to splits and cracks as well as to joints.The glue can be found in
several woodworking catalogues.

I haven't used it myself yet but plan to when next I need its properties. I
also heard mixed hide glue can be stored in the fridge to prolong its life.

 Phil E.