Previous Post Quote: It's been said in several places that Jerry's shrinking gas works differently than Pym's, hence the horrible deformity Jerry ended up with. Where are the several places this is mentioned? The 1985 handbooks says the methods are similar. Defenders #21 confirms Morgan began his experiments before Pym.

Morgan's gas has been described in Defenders as a cellular compression gas; the very same panel you're discussing in Defenders #21 calls it "cellular compression," which isn't how Pym particles work. Pym Particles don't compress matter, they provide a dimensional interface that enables one to send and retrieve mass across dimensional borders. Similarly, the original Handbook offers nothing except "cellular compression" in describing Morgan's gas.

The Headmen had an entry in the TPB version of the Deluxe Edition, but not in the original DE issues; I don't have my trades with me, and my paper copies are therefore no help here. The '89 version of the Handbook does remark that Morgan's gas "presumably" worked like Pym's stuff, but offers no definitive statement. It also refers to Morgan as "a genius in the organic sciences;" in contrast, Pym is both a biochemist and physicist, and Pym Particles combine Pym's two areas of expertise.

I don't think the '89 Handbook's presumption holds, though. Based on its use in the comics, Morgan's gas, unlike Pym Particles, don't allow a subject to retain their full human strength in a shrunken state, something we can infer from the times it's been used to render people helpless. Again, this shows that the mechanism is different, since Pym's gas usually allowed him to use his full-grown strength. If we go all the way back to the story that introduced him in World of Fantasy #11, we see that Morgan's gas temporarily shrinks only organic matter, which then quickly returns to its normal size. Pym Particles work on both organic and inorganic matter.

Finally, note that Morgan has never been able to master growth, just partially reversible shrinking. This is because his gas compresses cells, but he has not worked out how to add borrowed mass the way Pym Particles do. This also suggests that his shrinking gas and its antidote do not exchange mass across dimensional boundaries, or at least not the same dimensional interface that Pym Particles employ.

Morgan seems to have discovered a different mechanism for size change, one that's much less versatile and much less safe for use than Pym Particles. That's sort of the point of the three Headmen from the 1950s comics; they were the guys whose work was unsafe and a little off-brand, the guys who didn't become Pym, or Richards, or Strange, or even Doom because they went all in on defective processes or inferior methods.