d, till the
vari-colored lights persisted for a space of fully twenty seconds,
dancing and flashing in continuous play. Then I sat down, weak and
shaky.

"It's all up with me," I gasped, covering my eyes with my hands. "It has
attacked my eyes. Paul, take me home."

But Paul laughed long and loud. "What did I tell you?--the most
wonderful dog, eh? Well, what do you think?"

He turned partly from me and began to whistle. I heard the patter of
feet, the panting of a heated animal, and the unmistakable yelp of a
dog. Then Paul stooped down and apparently fondled the empty air.

"Here! Give me your fist."

And he rubbed my hand over the cold nose and jowls of a dog. A dog it
certainly was, with the shape and the smooth, short coat of a pointer.

Suffice to say, I speedily recovered my spirits and control. Paul put
a collar about the animal's neck and tied his handkerchief to its tail.
And then was vouchsafed us the remarkable sight of an empty collar and
a waving handkerchief cavorting over the fields. It was something to see
that collar and handkerchief pin a bevy of quail in a clump of locusts
and remain rigid and immovable till we had flushed the birds.

Now and again the dog emitted the vari-colored light-flashes I have
mentioned. The one thing, Paul explained, which he had not anticipated
and which he doubted could be overcome.

"They're a large family," he said, "these sun dogs, wind dogs, rainbows,
halos, and parhelia. They are produced by refraction of light from
mineral and ice crystals, from mist, rain, spray, and no end of things;
and I am afraid they are the penalty I must pay for transparency. I
escaped Lloyd's shadow only to fetch up against the rainbow flash."

A couple of days later, before the entrance to Paul's laboratory, I
encountered a terrible stench. So overpowering was it that it was easy
to discover the source--a mass of putrescent matter on the doorstep
which in general outlines resembled a dog.

Paul was startled when he investigated my find. It was his invisible
dog, or rather, what had been his invisible dog, for it was now plainly
visible. It had been playing about but a few minutes before in all
health and strength. Closer examination revealed that the skull had been
crushed by some heavy blow. While it was strange that the animal should
have been killed, the inexplicable thing was that it should so quickly
decay.

"The reagents I injected into its system were harmless," Paul expl