Sexing the shoggoth

The professor was having one of his funny turns in the study, and the butler, Fitches, was stationed in the doorway with a poker, a bucket of ice from the ice-house and a look on his face that would put the fear of God into small children and other household servants.  The cook had already been summoned and instructed to prepare a drench for the Professor that was to include no less than forty seven heads of garlic and a quarter-pound of onion skin.  The chambermaids had been summoned and told to change into their heaviest wet-gear and await further summons; they would be cleaning up the study after the Professor had been treated, calmed down, and safely put to bed.  The valet, Phillips, had been sent upstairs to the tower to get the bedroom there ready for the Professor, and to make sure that the windows were all tightly closed and locked.  Even Hubbins, the bird-wrangler, had been summoned in from his hedges and gardens and had spent five minutes in close, quiet conversation with Fitches before being dismissed again.  After that, there seemed to be rather more birds flying over the manor house than I recall seeing before, but I had no proof that that was Fitches had asked for, and it wasn't remarkable enough to pursue.
"You," said Fitches, gasping a little.  He was coated from head to toe in saliva that was viscous enough to drag behind him in rope-like strands.  It was white, smelled faintly of coconut, and appeared to be eating away at the iron poker.  "You're going to have to go down to the cellar, there's no-one else who can do it now."
"No," I said, my heart in my throat.  My hands were suddenly sweaty, and I had to resist the urge to rub them dry on my trousers.  "Miss Adelaide is here, she can go down to the cellar."
Miss Adelaide was the Professor's sister, five years his senior and a little batty.  In truth she was probably no odder than the Professor but we were used to his peccadilloes and little ways, while she was an unknown country and, we considered, best avoided.
"Not for this," said Fitches, his head turned so that he could see over his shoulder while still keeping on eye on me.  Saliva puddled on the floor around his feet.  "It'll have to be you.  They know your smell."
Just the words I didn't want to hear.  The things in the cellar that hunted by smell were things I didn't even want to dream of, let alone go and be in the same room as.  From time to time I had a nightmare that the Professor was teaching me to ride one of them and I was strapped onto its back by an unusual saddle that I couldn't free myself from.  The Professor, tall and saturnine in his stove-pipe hat that was a century out-of-date and out of fashion kept walking beside me, no matter how fast the beast turned and slithered and dashed.  From time to time he would tug thoughtfully on his goatee and then say something like, 'Don't let it get near the walls.  It can pass through the walls, and you can't.  We'll have to scrape you up and bury you in an envelope.'  I would shiver and hunch down further in my saddle, my fingers desperately picking at the knots and trying to get free.
The things in the cellar were shoggoths, obscene masses of silky, translucent flesh a little like water-fleas or perhaps rare specieses of slug.  They were lethal killing machines with no brain worth talking about.  They reacted purely on instinct, blindly snuffling towards heat and and light detected by some other senses, opening feeding-mouths all over themselves, but concentrated heavily towards what squishy bit was moving least erratically at the time.  They made for an excellent waste-disposal plan, and I knew that the Professor was looking for a way to weaponise them, but his fit seemed to be halting his work this morning.
"Go," said Fitches, his face looking suddenly tired as he saw something in the room behind him stirring again.  "And hurry.  You'll have to sex the shoggoths and separate them.  This is clearly linked to that problem."
I was half-way down the cellar steps when I suddenly realised something and stopped dead, one foot poised in mid-air to continue my descent.  I had only a small idea of what sexes Shoggoths did have, and I had no idea how to tell them apart.
"This should be interesting," I thought, listening to the howls from upstairs synchronising with the howls from below, and wondering just how much Fitches knew that he wasn't letting on.