GENERAL ZOOLOGY 



Fig. 5.10. Homunculus, as imagined to exist in 

 the head of the spermatozoon of man. (From 

 N. Hartsoeker, Essay de dioptnque, Paris, 1694.) 



not be seen. Spermatozoa were studied first in 1677 by Antony van 

 Leeuwenhoek, a Dutch microscopist. Several observers soon associated the 

 occurrence of spermatozoa in the seminal fluid with the phenomenon of 

 reproduction, and some workers stated that each spermatozoon contained a 

 fully formed, miniature individual. This tiny individual was called a homun- 

 culus and was believed to grow, nourished by the female, until the time of 

 birth (Fig. 5.10). Such a fantastic idea was opposed by other scientists of the 

 eighteenth century who believd that new individuals were fully formed in the 

 egg cells and that spermatozoa were parasitic in character and entirely un- 

 necessary for reproduction. These ideas of minute individuals encased in 

 spermatozoa or in eggs were responsible for the Theory of Preformation, 

 according to which development was simply the growth of a small individual 

 preformed in the so-called germ. 



140 



