40 
W. E. AGAR. 
the spermatocyte diakinesis. In this condition the chromo- 
somes, in the somatic number, are distributed round the 
periphery of tbe nucleus just under the nuclear membrane. 
In advanced stages they lose their regular shapes and become 
connected by numerous anastomoses. In one testis several 
spermatocytes in this stage have taken on all the characters 
of oocytes. 
The spermatogonial prophases are of a very simple nature, 
and show no sign of anything comparable to the stage of 
zygonema. 
In the spermatogonial and also in the somatic nuclei the 
chromosomes are arranged in a definite plan, the smaller and 
larger ones being grouped together. Within the main groups 
there is also evidence of a tendency for chromosomes of 
equal size to be next to each other. 
Bibliography. 
Arnold, G. — “ The Propliase in the Ovigenesis and the Spermatogenesis 
of Planaria lactea,” ‘ Archiv. f. Zellforscli.,’ iii, 1909. 
Calkins, G. N. — “The Spermatogenesis of Lumbricus, ‘ Journ. 
Morphol.,’ xi, 1895. 
Davis, B. M. — “The Reduction Divisions of (Enothera biennis/’ 
£ Annals of Botany,’ xxiv, 1910. 
Dingier, M. — “ Uber die Spermatogenese des Dicroccelium lan- 
ceatum Stil. et Hass.” (Distomum lanceolatum) , ‘Archiv. 
f. Zellforscli.,’ iv, 1910. 
Farmer, J. B., and Moore, J. E. S. — “ On the Meiotic Phase (Reduction 
Divisions) in Animals and Plants,” ‘ Quart. Journ. Micr. Sci.,’ 
48, 1905. 
Fick, R. — “ Zur Konjugation der Cliromosomen,” ‘ Archiv. f. Zellforscli.,’ 
i, 1908. 
Gates, R. R. — “A Study of Reduction in (Enothera rubrinervis,” 
‘ Bot. Gazette,’ xlvi, 1908. 
Goldschmidt, R. — “ 1st eine Parallele Chromosomen-konj ugation 
bewiesen ? ” ‘ Archiv. f. Zellforsch.,’ i, 1908. 
Grcgoire, Y. — “ Les Cineses de Maturation dans les deux Rcgnes,” (2e 
Memoir), ‘ La Cell.,’ xxvi, 1910. 
Gross, J. — “ Die Spermatogenese von Pyrrhocoris apterus,” ‘ Zool. 
Jahrb, Abt. fur Anat. u. Ontog.,’ xxiii, 1908. 
