Hergest Ridge

 
“Oh wearisome condition of humanity!
Born under one law, to another bound:
Vainly begot, and yet forbidden vanity;
Created sick, commanded to be sound.”
 
– Richard Fulke Greville

Ingenious experiments have shown that nerve cells, when they grow out from the spinal cord, or from the brain, find their way to their end organ not by following any kind of overall plan but by chemical attraction, rather as a dog sniffs around to find a bitch in season. An early classic experiment by the Nobel-Prize-winning embryologist Roger Sperry illustrates the principle perfectly.

Sperry and a colleague took a tadpole and removed a tiny square of skin from the back. They removed another square, the same size, from the belly. They then regrafted the two squares, but each in the other’s place: the belly skin was grafted on the back, and the back skin on the belly.

When the tadpole grew up into a frog, the result was rather pretty, as experiments in embryology often are: there was a neat postage stamp of white belly skin in the middle of the dark, mottled back, and another neat postage stamp of dark mottled skin in the middle of the white belly. And now for the point of the story. Normally, if you tickle a frog on its back with a bristle, the frog will wipe the place with a foot, as if deterring an irritating fly. But when Sperry tickled his experimental frog on the white ‘postage stamp’ on its back, it wiped its belly! And when Sperry tickled it on the dark postage stamp on its belly, the frog wiped its back.

What happens in normal embryonic development, according to Sperry’s interpretation, is that axons (long ‘wires’, each one a narrow, tubular extension of a single nerve cell) grow questingly, out from the spinal cord, sniffing like a dog for belly skin. Other axons grow out from the spinal cord, sniffing like a dog for belly skin. And normally this gives the right result: tickles on the back feel as though they are on the back, while tickles on the belly feel as though they are on the belly. But in Sperry’s experimental frog, some of the nerve cells sniffing out belly skin found the postage stamp of belly skin grafted on the back, presumably because it smelled right. And vice versa.

People who believe in some sort of tabula rasa theory – whereby we are all born with a blank sheet for a mind, and fill it in by experience – must be surprised at Sperry’s result. They would expect that frogs would learn from experience to feel their way around their own skin, associating the right sensations with the right places on the skin. Instead, it seems that each nerve cell in the spinal cord is labelled, say, a belly nerve cell or a back nerve cell, even before it makes contact with the appropriate skin. It will later find its designated target pixel of skin, wherever it may be. If a fly were to crawl up the length of its back, Sperry’s frog would presumably experience the illusion that the fly suddenly leaped from the back to belly, crawled a little further, then instantaneously leaped on the back again.

Experiments like this led Sperry to formulate his ‘chemo-affinity’ hypothesis, according to which the nervous system wires itself up not by following an overall blueprint but by each individual axon seeking out end organs with which it has a particular chemical affinity.

 
There is a story, which is fairly well known, about when the missionaries came to Africa. They had the Bible and we, the natives, had the land.
They said “Let us pray,” and we dutifully shut our eyes.
When we opened them, why, they now had the land and we had the Bible.
 
Desmond M. Tutu

What do WalMart, BestBuy, Procter & Gamble, and Travelocity have in common? Come to think of it, too much – forget I asked. But there is one thing I’d like for them and their likes to continue doing, and that’s pulling advertising money out from propaganda aired on FoxNews. (If this dream turns reality, FoxNews as a whole will go off air and the stupefied Under 50IQ Paranoiacs-R-Us will be left to wonder the streets, thus increasing their chances of getting killed by a speeding vehicle.)

Reports suggest that the list of companies requesting their advertisements not be part of Glenn Beck’s Duckspeak has now reached 20. (Source: The Huffington Post)

Even God is pleased; using angels’ blood He signed a self-imposed Cease to Kill Kittens, normally executed by the Almighty at a 1:1 ratio for each act of human masturbation. (Since the Reforms of ’79, acts of ape and chimp masturbation do not result in kitten executions. Ever since, humans have tried and failed to work out a similar deal with God, leaving many to feel shame and guilt over simply being human.)

The cease is valid on all days a new company pulls its advertising from FoxNews, a gesture which outraged the Mice Consortium, but to which the K9 Units responded with an enthusiastic wag of the tail.