144 
Thos. H. Montgomen-, jr. 
coine to behave dilfercntly from those of the gerni cells and even perhaps 
coine to lose their individuality. Change in chromosomal number and 
behavior might be a regulär concomitant of somatic differentiation, 
quite exclusive of any process of clu'omatin diminution. This is only a 
tentative hypothesis, but it may open up a new path in the investigation 
of the chromosomes. Whatever conclusions be reached for the tissue 
cells, however, need not in any way invaliditate the theory of the conti- 
nuity of the chromosomes as applied to the germ cells. 
Explanation of Plates IX & X, 
AU the figures are of the patemal germ ceUs of Eusehistus sp., from camera lucida 
drawängs, and are all made to the same scale with the exception of fig. 37 which is 
drawn to about half the scale of the others. 
The followäng abbreviatioms have been employed: 
a, acrosome; 
d, smaller diplosome; 
e, larger diplosome; 
fn, niicleus of foUicle cell of testis; 
i, chondriosome ; 
p, plasmosome; 
s, separated components (s-chromosomes) of a normaUy bivalent chromosome; 
t, trächea; 
X, supemumerary chromosome; 
y, yolk globales. 
Plate IX. 
AU the figures from ceUs of one testis (No. 282). 
Figs. 1 — 7. ceUs of foUicle 1: 
Fig. 1. Obüque view of a spindle of the first maturation. 
Figs. 2, 3. Lateral views of first maturation spindles. 
Fig. 4. Polar \-iew of second maturation spindle. 
Fig. 5. Lateral view of second maturation spindle. 
Fig. 6. Early spermatid. 
Fig. 7. Spermatozoon. 
Figs. 8 — 15. CeUs of foUicle 2 : 
Fig. 8. Polar new of spermatogonial monaster. 
Fig. 9. First spermatocyte, end of growth period. 
Figs. 10, 11. Lateral views of first maturation spindles. 
Fig. 12. Lateral view of second maturation spindle. 
Fig. 13. Early spermatid. 
Figs. 14, 15. Spermatozoa. 
Figs. 16—26. CeUs of foUicle 3: 
Fig. 16. Polar new of spermatogonial monaster. 
Fig. 17. First spermatocyte, end of growth period. 
