All figures were drawn with the camera lucida, on the table level, with one- 
twelfth oil immersion objective and ocular 18, except figures 15, 16, 18 and 39 to 
48 inclusive, which were drawn with ocular 4. Figures 41 to 48 inclusive have not 
been reduced. All others have been reduced one-third. 
PLATE 1 
EXPLANATION OF FIGURES 
Figures 1 to 18 inclusive represent cells fixed in Flemming’s strong solution, 
and stained according to Benda’s method, modified as stated on page 426. In 
all of these, the basi- or karyochromatin stains red-brown, the oxy- or plastochro- 
matin and its derivatives, the plastochondria, yellow, and the karyochondria 
dark blue. 
1, 2,3 Spermatogonia of different ages. 
4, 5, 6, 7, 8, 10, 11 Developing spermatocytes, which show the escape of the 
karyochondria from the nucleus into the cytoplasm, and the formation of yolk 
within them. Also the escape of the plastochondria from the nucleus into the 
cytoplasm, and the great increase in the relative amount of the cytoplasm. 
12 A fully formed spermatid. The mitochondria of Mayer or plastochondria 
of Meves are distributed radially around the chromatic mass throughout the 
‘perinuclear zone.’ 
14 A spermatid undergoing cytoplasmic reduction. 
15 A longitudinal section of a fully formed spermatozoon. 
17 A spermatozoon in the ‘entrance region’ of the uterus, showing no trace 
of the refractive body. 
18 An egg in the metaphase of first cleavage. The chromosomes are not cut, 
so that the karyochromatin is entirely hidden by the karyochondria. The astral 
rays, centrosome, etc. are distinctly yellow. 
19 to 27 Cells fixed in the Carnoy-Lebrun acetic fluid, and stained in the Ehr- 
lich-Biondi stain. In these the karyochromatin is green, the plastochromatin and 
plastochondria red, and the yolk vesicles purplish (not so dark as in the colored 
figures). Thekaryochondriaare not tobe distinguished from the karyochromatin 
in cells stained in Ehrlich-Biondi. 
25 Fusion of the yolk vesicles preparatory to the formation of the refractive 
body in the vas deferens. 
27 A spermatozoon in the ‘entrance region’ of the uterus which has almost 
entirely consumed its food supply (the refractive body) during its journey. 
28 Here the food supply is entirely gone. This cell was fixed in acetic-alco- 
hol, a modification of Zur Strassen’s fluid, and stained in iron-hematoxylin and 
Bordeaux red. The plastochondria take the latter. 
29 A spermatogonium fixed in acetic-alcohol and stained in iron hematoxylin 
alone. The plastochondria (plastosome) here stain jet black. 
450 
