Now that I'm home from work, I'm able to see that Puckett's noticeably skinnier, this evening, than he was last night before bed. I can actually see his heart beating through his chest (though, at least, his breathing doesn't seem labored, right now) and his face is so bony-looking.
I'd end it, tonight, but I'm not about to do something that requires me using the "night depository" at the pet crematorium. He deserves better than being left in a drop-box, even if what would be left wouldn't really be him.
I've got stuff at work that pretty much has to be done, or I"d do it tomorrow, during the day. Fortunately, both the vets that have been seeing after him, the past few years, are on duty, Friday. So, assuming he can wait that long (or doesn't experience some kind of miracle before then), we'll take him in and send him off.