62 Bulletin Wisconsin Natural History Society . [Vol. 10, Nos. 1 & 2. 
In 1745, Bonnet published a rather full account of partheno¬ 
genesis in the plant lice. His experiments showed careful and 
painstaking observations and they attracted the attention of many 
brilliant investigators. 
The most important work on the subject, however, has been 
done within comparatively recent years. Dzierzon, in 1845, pro¬ 
duced his now famous results on the parthenogenetic development 
of the unfertilized eggs of the common bee, “Apis mellifica” and 
this may be said to mark the beginning of all modern investigation 
into the problem. His work is extremely interesting from the 
standpoint of sex determination, for it has stimulated more experi¬ 
mentation on the subject than any of the researches of his pre¬ 
decessors. Concerning his theory more will be stated in our dis¬ 
cussion of the individual parthenogenetic groups. 
With this short sketch of the subject, let us now turn to a 
more direct discussion of parthenogenesis. 
The word parthenogenesis is derived from the Greek, and its 
literal translation is, “a virgin production.” The word was first 
used by Owen in 1849, m the sense of alternation of generations. 
Ernst von Siebold, on the other hand, in 1856, applied the term 
parthenogenesis to the development of eggs without fertilization, 
and this latter definition is the one universally in vogue among 
zoologists today. 
Broadly speaking, parthenogenesis may be classified into, 
1. natural parthenogensis, where parthenogenetic 
development occurs as a part of the normal life-history of the 
species, and 
2. artiEical parthenogenesis, where development 
occurs through an artificial stimulus, either chemical or physical. 
The wonderful progress that has been made within recent 
years along the line of artificial parthenogenesis, has disclosed 
many facts concerning the mechanics of fertilization and of 
development. Natural parthenogenesis, on the other hand, has 
given us direct insight into the difficult problem of sex. With this 
phase of the subject I wish to deal rather fully. 
B. NATURAL PARTHENOGENSIS. 
The most frequent form of natural parthenogenesis occurs in 
those species where parthenogenetic generations alternate with 
