lOO EISEN. [Vol. XVII. 



XII. EXPLANATION OF THE FIGURES. 

 Plates I-XIV, Figs. 1-122. 



General Remarks. — All the figures have been drawn to the same scale projec- 

 tion on the working table, by the aid of a Griinow drawing camera and with a 

 Zeiss Apochromat, 3 mm., Ap. i, 40, Oc. 18. The details were studied with a Zeiss 

 Apochromat, 2 mm., Ap. i, 40, Oc. 12, the magnification thus being in both 

 instances about 1500. An achromatic oil-immersion substage condenser was 

 used for all detail work, and it was always supplemented by an achromatic light- 

 filter as described under the heading of methods. A few of the figures, as stated 

 in the text, have been drawn from Oc. 18, and with 2 mm. Objective. The stain- 

 ing, with the exception of a few, has been the same for all the sections: iron- 

 haematoxyhn, with after-staining with congo. A few preparations were stained 

 with congo-thionin-ruthenium red. The sections were cut about 5 \t, thick and 

 affixed to the slides by the alcohol method. All the figures are from the testes 

 cells of Batrachoseps attenuatus Esch. Fixative exclusively iridium-chloride-acetic. 



The figures have principally been arranged according to the serial development 

 of the nucleus, and not according to the development of the spheres and the 

 spindle. In the later stages of the spermatocytes the figures have been partly 

 arranged according to the development of the spindle. The figures in the text 

 are strongly diagrammatic. 



Large Polymorphous Spermatogonia {Figs. i—g). 



Fig. I. Large polymorphous spermatogonium, perfect resting stage. The 

 large black body is the chromoplast surrounded by filaments of linin stained red. 

 The chromoplast contains several highly refractive endochromatic granules. The 

 large red body is the linoplast. The small granules, of uniform size and dark 

 color, are the chromioles. The lighter stained granules are partly chromioles, 

 partly linin granules, all of which are suspended in the linin network. A number 

 of parachromatic granules are seen around the chromoplast. The cytoplasm has 

 the form of a thin hollow shell surrounding the much folded nucleus. Two cen- 

 trosomes in the cytoplasm. Remains of, or the beginning of, a granosphere at the 

 top of the cytoplasmic shell. The dark-staining granules which form a shell 

 around the linoplast are the paranucleolar granules. 



Fig. 2. Large polymorphous spermatogonium, perfect resting stage ; the chro- 

 moplast is larger and divided in two nearly equal parts, and is surrounded by an 

 aster of linin threads of even length; at the tips of the threads are seen more dis- 

 tinct linin granules. The granosphere is being reconstructed at the upper end 

 of the nucleus, but in the cytoplasm. No centrosomes visible. A large lino- 

 plast with paranucleolar granules. 



FjG. 3. Polymorphous spermatogonium in a more advanced stage than Figs. 

 I and 2, but still in the resting stage. The chromioles, which are strung on 

 threads of linin and chromoplasm, are being drawn towards the chromoplast, the 

 leaders thus beginning to form. Two linoplasts of unequal size stained red. 

 The nucleus is less polymorphous than in Figs, i and 2. The cytoplasmic 

 granules are more scattered, forming a more extended and less ring-shaped cyto- 

 some. Centrosome in the granosphere. 



Fig. 3 b. Detail of the granular reticulum or network of the linin. 



