132 The Spermatogenesis of Desmognathus Fusca 



Spengel, 76. — Das Urogenitalsystem der Amphibien. Arbeiten des zoolog'.- 



zootom. Instituts in Wlirzburg, Vol. Ill, Ileft. 1, 1876. 

 La Valette, St. Geoege, 76- — Ueber die Genese der Samenkorper. Die 



Spermatogenese bei den Amphibien. Arch. f. milir. Anat., Vol. XII. 

 Steassburgek, E., u. Mottier, 97. — Ueber den zweiten Theilungsschritt in 



Pollenniutterzellen. Ber. d. Deutsch. Bot. Ges., Vol. XV, nr. 6. 

 VAN der Stricht, 98. — Contribution a I'etude, de la forme, de la structure, 



et de la division du noyau. Bull, de I'acad. de Belgique, Ser. 3, 



T. XXIX, 1898. 

 ToYAMA, 94. — On the Spermatogenesis of the Silk-worm. Bull. Agr. Coll. 



Imp. Univ., Tokio, Vol. II, No. 3. 

 Wbismann, a., 87. — Ueber die Zahl der Eichtungskorper und iiber ihre 



Bedeutung fiir die Vererbung. Jena, 1887. 

 Weismann, a., 93. — The Germ-plasm. New York. 

 WiiiDEK, H. H., 99. — Desmognathus fusca (Eafinesque) and Spelerpes bili- 



neatus (Green). Am. Nat., Vol. XXXIII. 

 Wilson, E. B., 00. — The Cell in Development and Inheritance. The Mac- 



Millan Co., New York, 1900. 

 VON WiTTiCH, 53. — Beitrage zur Morphologische und Histologische Ent- 



wicklung der Ham und Geschlechtswerkzeuge der nakten Amphi- 

 bien. Zeitschr. f. wiss. Zool., Bd. IV, 1853. 

 Zeller, Ebnest, 90. — Ueber die Befruchtung bei den Urodelen. Zeitschr. 



f. wdss. Zool., Vol. XLIX, pp. 583-602, 1890. 



Explanation of Plates. 



All the figures of the tour plates are drawn at the same magnification 

 with a Leitz microscope, draw-tube in, Leitz 1/16 in. immersion objective, 

 and Leitz No. 4 Ocular. All figures on plates III and IV are reduced only 

 Yz the extent of plates I and 11. % was taken off any diameter of figures 

 on plates I and II. Only i/g taken off any diameter of figures on plates 

 III and IV. Hence take 14 more off any diameter of a figure on last two 

 plates, to compare size with a figure on first two plates. All were drawn 

 from longitudinal sections of Desmoffnathxis testes, fixed in Hermann's 

 fluid (except Fig. 7, where the fixer was Flemming's chrom-aceto-osnaic 

 mixture, strong formula) and stained with Heidenhain's iron hematoxylin. 

 The sections from which they were drawn, were paraffin sections, 10 and 

 7 fi thick. 



PLATEIS I AND II. 



Division of Spermatocyte I. 



Fig. 1. Secondary spermatogonium of the last generation, showing as 

 yet no indication of the beginning of the growth period. 



Fig. 2. Spermatocyte soon after the beginning of the growth has be- 

 come evident. The chromatin is becoming arranged in the form of 

 threads. A nucleolus is shown. 



Fig. 3. Spermatocyte, later stage of growth; spirems larger and better 

 defined. Indication of the chromosome threads vdth their free ends 

 towards the idiozome. 



