THE SPERMATOGENESIS OF LEPIDOSIREN PARAPOXA. 1 
The Spermatogenesis of Lepidosiren 
paradoxa. 
By 
W. E. Agar, M.A., D.Sc., 
Zoological Laboratory, Glasgow University. 
With Plates 1-5 and 1 Text-figure. 
Contents. 
page 
Introduction ..... 
Methods ..... 
The Number of Chromosomes 
The Germinal Epithelium .... 
The Meiotic Divisions .... 
Nomenclature ..... 
The First Meiotic Division .... 
The Second Meiotic Division 
Intercalation of a Resting Stage in the Meiotic Prophase 
The Pre-meiotic (Spermatogonial) Divisions 
The Reduction Question . . . 
Bearing of the Conditions in Lepidosiren upon the Nature of the 
Copepod type of Tetrad 
Reality of Parasyndesis .... 
Significance of the Temporary Complete Separation of the Ex 
conjugants in Diakinesis . . . 
Pairing of Chromosomes outside the Meiotic Period 
Summary ..... 
1 
4 
5 
5 
8 
8 
8 
21 
23 
29 
34 
37 
39 
Introduction. 
The material for this work was obtained during an expedi- 
tion to the swamps of the Paraguayan Chaco, undertaken 
VOL. 57 , PART 1 . NEW SERIES. 1 
