1907] GATES—POLLEN DEVELOPMENT AND MUTATION II5 
PLATE IV } 
Fics. 35-42. O. Lamarckiana (dominant). 
Fic. 35. Another equatorial view; the unequal appearance of the members of 
a pair may be due to foreshortening. 
Fic. 36. Heterotypic spindle showing tendency of chromosomes to arrange 
themselves in groups of more than two. 
Fic. 37. Early anaphase, showing viscid consistency of some of the chromo- 
somes; the number is at least twenty; no heterochromosomes present; iron-haem- 
atoxylin-orange; 7.56. X1500. 
Fic. 38. Late anaphase, showing premature splitting of the chromosomes for 
the homotypic division; twenty chromosomes present; 7.5 #. 1500 
IG. 39. Late anaphase; one chromosome lagging behind on the spindle, 
and shige chromatic bodies in the cytoplasm; 7.5 #. X 1500. 
pont in which the reconstruction of the daughter nuclei has 
begun; 7 
IG. 41. On of the daughter nuclei in the early stages’ of reconstruction; 
remnants of the spindle still connect it ee the sister nucleus; several large 
chromatic bodies are found in the cytoplasm; 7.5 
Fic. 42. Polar view of daughter rtuelens in late stage of reconstruction; 
iron-haematoxylin-orange; 10 #. 
Fics. 43-51. O.lata (dominant). 
Fic. 43. Pollen tetrad, showing three of the four nuclei; the latter vary in size 
and in chromatin conten 5: the tetrads are still attached to each other at the ends, 
but free oe 5H. 25. 
- . Same as io but nuclei of nearly equal size; safranin-gentian-orange; 
5 #. 1 men 
Fic. 45. Tetrad showing first appearance of walls; chromatic bodies in the 
en 54. X122 
G. 46. Tetrad showing two extra nuclei attached to one of the daughter 
nue 54. X1275. 
G. 47. Tetrad after wall formation, showing extra nuclei, and chromosomes 
in Pg cytoplasm not surrounded by a nuclear membrane; 8 #. X 1225. 
Fic. 48. Section of a tetrad, showing a small extra nucleus, formed by one 
chromosome, connected by spindle fibers with one of the larger nuclei; 5 4. X 1225. 
IG. 49. Portion vie a tetrad showing a small extra nucleus beside one of the 
tetrad nuclei; 5 . 225. 
FIG. 50. pe cacs. of tetrad pis two small extra nuclei, each containing 
two chromosomes; 5 #. X212 
Fr. ies 625 Tetrad showing ee nuclei, and chromatin in the cytoplasm; 
8 au, 
se IG. ae Young pollen grains of O. Lamarckiana (dominant); a shows a 
normal-shaped grain; grains showing various abnormalities, such as those illus- 
trated, are of frequent occurrence. X 310. 
