40 SPOLIA ZEYLANICA. 
arises, not in the finding of facts which controvert our theory, 
but in the perception of them. Once convince yourself of the 
truth of any hypothesis and you receive a mental bias, by 
means of which, albeit unconsciously, you correlate your 
observations with the inevitable result that they aie made to 
fall in line with your preconceived ideas. You are led to 
confuse theory with observation, and fact with inference. 
A notable example of this curious visual distortion is to be 
seen in the predelineation (or evolutio) theory. This theory 
maintained that the development of animal life was much the 
same as the unfolding of a bud. The immature animal was 
considered to exist 7n toto within the reproductive cell, which 
merely required a certain stimulus to start its growth. This 
theory was a product of the seventeenth century, and is 
associated with the great names of Swammerdam, Malpighi, 
and Leeuwenhock. 
Malpighi observed evidence of organization in an unincu- 
bated egg in 1672 (during an Italian summer, be it noted). 
Swammerdam had made observations of insects in a chrysalis 
stage and of caterpillars about to enter the pupa condition, 
in which he discerned the outlines of the organs of a future 
state. Leeuwenhock made the discovery (often wrongly 
attributed to Hartsoeker) about 1676 of fertilizing filaments 
in eggs. This led to a controversy as to whether the embryo 
pre-existed in the egg or in the sperm. The egg was regarded 
by some as a nidus, within which the sperm developed ; others 
declared the ovum to carry the embryo, and regarded the 
sperm as a stimulant for growth. Thus arose the rival schools 
of animalculists and ovulists. The debate over the details of 
the preformation theory gave way to the wildest speculations, 
and some ingenious persons computed the number of eggs, 
which must have been encased one within the other (like a 
Japanese juggler’s boxes), within the ovary of Mother Eve. 
The astonishing answer to this remarkable problem in bio- 
metrics was two hundred millions. Meanwhile Hartsocker, 
who was a confirmed animalculist, gave the world a drawing 
of a spermatozoon, in which a little man was to be seen crouch- 
ing with his knees tucked up under his chin, and Hartsoeker 
seems actually to have believed that he had seen the little man. 
