50 
H. E. Jordan 
VI. Secondary (dimorphic) Spermatocytes. 
a) Hosting Phase. 
The dimorphism of the secondary spermatocytes is expressed in the 
resting stage (this appears to be omitted in some instances) by the pre- 
sence in approximately one-half of a chromatin- (chromosome) nucleolus. 
The latter is nsuaUy close to the centrospliere (fig. 41). The nucleus 
contains also several, usually three, plasmosomes. Chromidia are again 
seen passing out of the nucleus into the cytoplasm (fig. 39). Mitochondria 
mass at one point on the nuclear membrane (figs. 39 and 40). Similarity 
in shape to the mitochondria of earlier stages indicates identity and 
simple persistence. Their characteristic clumping at one or several points, 
and close to the nuclear membrane, indicates an origin anew. However, 
they do not have the specific and uniform shape of the original chromidia 
of the primary spermatocytes. Again only their form, presence and 
Position is clear. Partial nuclear origin is inferred from the presence of 
intra- and extra-nuclear basichromatin granules (fig. 39). Persistence 
is demonstrated by the fact of their presence in late anaphase of the 
first division (fig. 38). 
b) Second Maturation Division (equational). Hemioid Chromosome 
Group. 
Equatorial plates of second maturation spindles are of two types: 
one contains 4 chromosomes (figs. 42, 43 and 44) : the other 5 chromo- 
somes (figs. 46 to 52). Most of the chromosomes appear bipartite. In 
the plates of 5 chromosomes, one is usually larger (figs. 50 and 51). This 
is the undivided accessory. In metakinesis all the chromosomes behave 
similarly: i. e., tliere is apparently no lagging behind of the accessory 
as described for many forms (e. g. man, Guyer 1910; Aplopus mayeri, 
Jordan 1907). Anaphase figures vary in that some have 4 chromosomes 
at the poles (figs. 45 and 54), others have 5 chromosomes (figs. 48 and 53). 
Figs. 55 and 56 illustrate successivelv later telophase stages. There ob- 
tains here a second pairing of chromosomes such as Guyer has described 
for pigeon (1903), rooster (1909b), guinea-fowl (1909a) and man (1910), 
giving rise to a hemioid chromosome group. The 5 chromosome group 
is interpreted as due to a pairing of 8 of the chromosomes resulting from 
the first maturation division plus the unpaired accessory chromosome 
at one pole (daughter secondary spermatocyte); the 4 as the result of a 
pairing of the 8 chromosomes at the opposite pole. 
