52 GERM-CELL CYCLE IN ANIMALS 



the work of the above named investigators there were 

 many who were not convinced that paedogenesis 

 occurs in the genus, and the larvae which were 

 known to develop within the bodies of other larvae 

 were considered by these skeptics as parasites. How- 

 ever, the results of Kahle's (1908) studies, which have 

 been decisively confirmed (Hegner, 1912, 1914 a), 

 have finally settled the question in favor of paedogen- 

 esis. 



Previous to 1910 no specimens of the genus 

 Miastor had been recognized in this country, but 

 on Oct. 5 of that year, Dr. E. P. Felt found them in 

 great abundance, living in the partially decayed 

 inner bark and in the sap wood of a chestnut rail. 

 With material supplied by Dr. Felt, the writer 

 has been able to follow the entire keimbahn in these 

 insects. Paedogenetic reproduction normally oc- 

 curs during the spring, summer, and autumn, multi- 

 plication being arrested during the cold winter 

 months. This method of reproduction is interrupted 

 in midsummer by the appearance of male and female 

 adults. 



The larva of Miastor possesses two ovaries, one on 

 either side of the body in the tenth or eleventh 

 segment. Each ovary (Fig. 12) consists of typically 

 thirty-two oocytes (ooc.ri) ; these are inclosed in a 

 cellular envelope (en) . Associated with each ob'cy te 

 is a group of mesoderm cells which function as nurse 

 cells (n.c.) and together with the oocyte are sur- 

 rounded by a follicular epithelium (f.ep). The 

 nurse cells furnish nutrition to the growing oocytes, 



