_ubi_ of
spirits. The smattering I have [in the knowledge] of the
Philosophers stone ... hath taught me a great deale of Divinity,
and instructed my beliefe, how the immortall spirit and
incorruptible substance of my soule may lye obscure, and sleepe a
while within this house of flesh. Those strange and mysticall
transmigrations that I have observed in Silkewormes, turn'd my
Philosophy into Divinity. There is in those workes of nature, which
seeme to puzzle reason, something Divine, and [that] hath more in
it then the eye of a common spectator doth discover.[30]

To affirm that Sir Thomas Browne was the founder of chemical embryology
or, indeed, to contend that he made a great impress upon the progress of
embryology is to humour our fancy. As Browne himself reminds us, "a good
cause needs not to be patron'd by a passion."[31] His work and
interpretations of generation are most important for our purposes as an
indication of the rising mood of the times and an emerging awareness of
the physiochemical analysis of biological systems. Although this mood
and awareness coexist in Browne's writings with a continued reverence
for some traditional attitudes, they mark a point of departure toward a
variety of embryological thought prominent in England during the second
half of the seventeenth century.

Browne did no more than analyze crudely the reaction of the egg to
various physical and chemical agents. This static approach was later
supplanted by a more dynamic one concerned primarily with the
physicochemical aspects of embryonic development. This is first apparent
in a report by Robert Boyle in the _Philosophical Transactions of the
Royal Society_ in 1666 entitled, "A way of preserving birds taken out of
the egge, and other small foetus's." Boyle, unlike Browne, exposed
embryos of different ages to the action of "Spirit of Wine" or "Sal
Armoniack," demonstrating thereby the chemical fixation of embryos as an
aid to embryology. A year later, Walter Needham, a Cambridge physician
who studied at Oxford in the active School of Physiological Research,
which included such men as Christopher Wren and Thomas Willis, published
a book reporting the first chemical experiments upon the developing
mammalian embryo.[32] Needham's approach and goals are more dynamic than
those of Browne, and he attempts to analyze various embryonic fluids by
coagulation and distillation procedures. His experimen