New updates to the Devil’s dictionary!!!

today’s entries: blastulation, chorion, latebra, and reproductive value.

See the complete Devil’s Dictionary of Scientific Words and Phrases here.


all entries in the Devil’s Dictionary copyright 2019 by Russ Hodge


blastulation  A process in an early stage of embryogenesis whereby cells form a hollow, balloon-like sphere (or blastula, although any Latin nerd will tell you it ought to be called a blastulum, just as the singular form of spatula ought to be spatulum). In ancient times, before evolution got things straightened out, blastulas (or blastula, depending on your stance on the spatula/spatulum issue) often suffered the fate of balloons being overinflated. They blasted apart, hence the name. Then evolution produced gastrulation, which had basically the function of adding extra layers to the balloon so that it could expand to the size of a whole animal without exploding.

chorion  The yucky, skin-like envelope still left on the surface of an egg after the shell has been peeled off, if you didn’t properly follow the manufacturer’s protocol for boiling an egg. Whether the chorion is also there before the egg has been boiled is a matter of intense controversy among chorionologists. One school holds that it is indeed there, while the other maintains that the chorion is an artifact that arises through the process of boiling, like the skin that forms on boiling milk. The question has not been resolved because so far, all attempts to peel unboiled eggs have resulted in a state of affairs technically known as a mess.

latebra  The white stuff in an egg – in other words, everything except for the yolk, the shell, the chorion, parasites, other visitors, GPS tracking devices, or any foreign entities you might find there. Whether the latebra is white before you open the egg is a philosophical question on a par with the light-in-the-refrigerator debate.

reproductive value  A quantitative value assigned to females which represents the number of children they will still have once they have reached a particular age. For a female aged x, for example, the reproductive value would be represented as Vx. If the female is aged x + 3, then the reproductive value would usually be lower, unless she is a late starter, or has yet to attract a partner, or has an unenthusiastic partner, or is taking potent fertility drugs, or her partner is taking such drugs, at which point things get rather unpredictable and the formula becomes more complex. The reproductive value also depends on the species in question, and whether the “3” represents years, months, or minutes; in any case the value should be adjusted by subtracting the number of children the female had during the 3 years, months or minutes that have passed, yielding a formula something like Vx + 3 = Vx– y, where y = the number of children she could have had during that period, although if she bore twins this should be corrected to 2y, triplets 3y, octuplets 8y, etc.


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I am a science writer at the Max Delbrück Center for Molecular Medicine in Berlin, author of fiction and popular science books, an artist, and a professional musician who performs on the viola da gamba and Medieval and Renaissance stringed instruments. I edit manuscripts of all types and teach the full range of scientific communication skills. I am doing theoretical work in this subject - see for example

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