Ephemeri vita, or, The natural history and anatomy of the Ephemeron, a fly that lives but five hours written originally in Low-Dutch by Jo. Swammerdam ...
Swammerdam, Jan, 1637-1680., Tyson, Edward, 1650-1708.

CHAP. VII.

Signs of the Worms being ready for Change; what is hurt∣ful to it; and to which order of Natural Change it per∣taineth.

THE common preceeding signs of the Worms Change at the exact season of the year, are a Warm and dry Spring, a Mild Winter, little Rain and Snow, and a soft gliding water. The particular signs that the Worm will soon fly, are the swelling of the Wing-cases on the back, which at that time attain a thicker and rounder form than formerly; whereby the watery Gluiness which otherwise is found in the Wing-cases is now become tougher and thicker, so that it now beginneth to attain the shape of the Wing, and appear through (b) the transparent Wing-cases.

These signs are yet more apparent when the Colour of these inclosed Wings change from a Pale Yellowish*Page  28 into a Grey colour; and yet more certain, when the Wing-cases can be separated from the Wings, without hurting them; as in Tab. 3. (hhh) is represented, where the Wing is represented at large with its natural but rare pleatings.

A further sign thereof is, when Dissecting the Worm the Eggs are found to be full grown, hard, and Oval, and also when the outward case may be clearly separa∣ted from the Worm and thereby cause it to attain the form of the flying Haft or Ephemeron.

At this time all their Intestines are cleared of all faeces; the Stomach and Guts containing nothing but transparent and purified liquor, which the further from Change they are, the more Clouded and Coloured they are found; their Colour being sometimes Yellow∣ish, and sometimes dark and Russet; at other times there is found backward in the thick and straight Gut a little Clay, whereas being now ready for Change, they are very clear and transparent.

That which retardeth the Change of the Worm, killeth it, and hindreth its Change, is a hard and long Winter, much Snow and Rain, whereby their Cells are closed, broke, or covered with Sand, whereby they come forth both fewer in number, and later in the one year than the other. They are also hindred by too much drought, which forceth them to leave their Cells, and bore new ones, from all which may be discerned what hindereth or furthereth the Worms growth.

Many water and other Insects are found to be infested with Lie; which extendeth so far, that even no Creature living either on Land or Water, that hath not its peculiar Louse, which feedeth on its bloud and moisture, even from the great Whale to the small Ant.

From what hath been now related of the Signs of the full growth of the Worms Wings, it clearly ap∣peareth to which of the Four Orders of Natural Change, or slow growing on of the Limbs it pertain∣eth; viz. to the Second Order, for all the Insects there∣unto Page  29 belonging, change in the same manner like our Worm: Which Second order of Change is, That the Worm of the Ephemeron having quitted its Egg or Shell. comes forth a Six-footed Worm, and by nourishment re∣ceived, increaseth in all its Limbs to a full growth; so that now on its back appear the Wings budded out; until it be grown ito a Nympha; which loseth not its motion, and afterwards attaineth the shape of a Flying Creature, by the shedding of its upper Skin or Coat, whereby it now becometh fit for Generation. As of this and other like Changes I have treated more at large in my Treatise of Insects, where I have enumerated a great number belonging to this second Order.

Angerius Clutius supposeth that our Worm Changeth into a Nympha of the Third Order, and then like the Nympha of the Silk-worm it loseth all motion, which he also representeth in Figure, although in truth it is otherwise; from whence may appear how easily they may be mistaken, who declining the Truth of Experi∣ence, only depend on their own Reasonings or the Affirmations of others.