This constitutes something of a misreading of the kinds of experiments Erasmus Darwin
recounts in the first of his Additional Notes—"Spontaneous Vitality of Microscopic
Animals"—appended to The Temple of Nature. Probably Mary Shelley is taking figuratively,
as a kind of macaroni, the literal meaning of "vermicelli," tiny worms—what Darwin
calls "microscopic animalcules." Still, although she humorously exaggerates the kind
of spontaneous generation that drew scientific speculation in the early years of the
nineteenth century, it is important to recognize how seriously such experiments were
taken. Here, for instance, is the initial sentence of Darwin's "Conclusion":
{8} There is therefore no absurdity in believing that the most simple animals and
vegetables may be produced by the congress of the parts of decomposing organic matter,
without what can properly be termed generation, as the genus did not previously exist;
which accounts for the endless varieties, as well as for the immense numbers of microscopic
animals.
Percy Bysshe Shelley also cites Erasmus Darwin in the first sentence of his Preface
(I:Pref:1) to the 1818 edition.