AND OF HYBRID PIGEONS. 
7 
the platino-sublimate-acetic mixture mentioned above. They 
then stain very readily with either cyanin and erythrosin or with 
the Biondi-Ehrlich triple stain. Spermatozoa killed in osmic 
acid vapor and stained in Saffranin, also afford good material 
for study. 
GENERAL ARRANGEMENT OF THE GERMINAL CELLS. 
But little detail need be given regarding the general struc¬ 
ture of the testis in the pigeon, for it does not differ essentially 
from that of well known mammalian forms. The spermato¬ 
genesis of the rat is especially well known through the re¬ 
searches of Von Ebner^, Lenhossek^ and others. In the pigeon 
the testes are two elongated bean-shaped organs varying much 
in size with age and with individuals. The germinal cells are 
laid down in a very great number of convoluted tubules which 
wind back and forth throughout the interior of each testis and 
make up its main bulk. The tubules are much slenderer and 
more delicate than those of the rat, however, and can not be 
isolated so readily for study. 
In the arrangement of the germ cells in the tubule, there is 
no departure from that of the other warm-blooded animals. 
Next the walls are the spermatogonia or parent cells (Fig. 1, 
sg.), which by growth and division give rise to the various gen¬ 
erations of germ cells lying inward toward the lumen. The 
adult spermatozoa are formed through the final transformation 
of the spermatids, or cells produced by the last division, which 
lie nearest the center of the tubule. The ripe spermatozoa 
pass out through the lumen of the tubule and into the ducts 
which lead to the exterior. As in many forms, the spermatozoa 
attach themselves to a supporting cell (Fig. 1, s) for a period 
before their complete maturation and ejection from the testis. 
The usual four phases or types of the germinal cells are rec¬ 
ognizable, viz: (1) spermatogonia (Fig. 1, sg.), a more or less 
regular layer of cells lying next to the membrane or wall of the 
tubule, each cell of which through division gives rise to two 
new cells. One or both of these may increase in size and be- 
1. Von Ebner, V: “Zur Spermatogenese bei den Saugetbieren.” Arch. f. 
mikr. Anat., XXXI., 1888.. 
2. Loc. cit., p. 5. 
