PLATE 1 « 
A. — Euchlaena perennis Hitch. Heterotypic prophase, 19 bivalent and 2 
single chromosomes. 
B. — Euchlaena perennis Hitch. Heterotypic metaphase. 
C. — Euchlaena perennis Hitch. Heterotypic anaphase. 
D. — Euchlaena perennis Hitch. Early homotypic metaphase. 
E. — Euchlaena perennis X Zea mays . Th. 9522. Heterotypic prophase, 7 
trivalent, 4 bivalent, and 1 univalent chromosome. 
F. — Euchlaena perennis X Zea mays . Th. 9522. Heterotypic metaphase, 
3 trivalent, 8 bivalent, and 5 univalent chromosomes. 
G. — Zea mays X Euchlaena perennis. Th. 10322. Heterotypic metaphase, 
2 trivalent, 11 bivalent, and 2 univalent chromosomes. 
H. — Euchlaena perennis X Zea mays. Th. 9322. Heterotypic anaphase; a 
typical irregular chromosome distribution. 
I. — Euchlaena perennis X Zea mays (pod). Th. 9022. Late heterotypic 
anaphase. 
J. — Zea mays X Euchlaena perennis. Th. 10322. Interkinesis showing two 
major nuclei and two minor nuclei. 
K. — Zea mays X Euchlaena perennis. Th. 10222. Homotypic divisions. 
• The plates reproduce camera-lucida drawings of different phases in the reduction divisions of pollen 
mother-cells of several representative Tripsaceae. A 1.7 mm. oil immersion objective, a No. 12 compen¬ 
sating ocular, and cells stained with iron-acetic-carmine were used in preparing these drawings, except 
as follows: Heidenhain’s iron-alum haematoxylin was used for staining PI. 1, G to K; PI. 2, A, D, G; PI. 
3, C and D, E to I. An ocular No. 18 was used for PI. 2, A, D, G, and for PI. 3, A. So far as possible, 
the drawings give details in size and shape of the individual chromosomes, thus allowing a comparison of 
chromosomes in any particular species or between closely related species. (Reduced one-third in repro¬ 
duction.) 
( 682 ) 
