CHAPTER III 
THE GERM-CELL CYCLE IN THE PHDOGENETIC 
FLY, MIASTOR 
Tuus far in only one genus of animals has the 
history of the germ cells from one generation to the 
next been followed in detail through the entire 
cycle. This is a genus of flies, Miastor, of the family 
Cecidomyidee. One species, Miastor metraloas, oc- 
curs in Europe and has there been studied especially 
by Leuckart (1865), Metschnikoff (1865, 1866), and 
Kahle (1908), and the only other species that has 
been investigated is M. americana (Hegner, 1912, 
1914a). 
Peedogenesis in Miastor was discovered by Wagner 
in 1862, and was confirmed by Meinert in 1864. 
In 1865 the first investigations of its embryological 
development were published by Leuckart and Metsch- 
nikoff. These were the earliest accounts of the 
keimbahn in any animals. Only a glance at Metsch- 
nikoff’s report is necessary to convince one of the 
favorableness of Miastor as material for germ-cell 
studies. The primordial germ cell is shown to be 
established at a very early period in the cleavage of 
the egg, and the descendants of the primordial germ 
cell are quite easily distinguishable from other cells 
in the body even in in toto preparations. In spite of 
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