PLATE IV. 
Zamia floridana and Zamia pumila, 
Fig. 40. Spermatid with section of ciliferous band in cytoplasm, showing protuber- 
ances on outer side. (X 600 diam.) 
Fig. 41. Spermatid with section of ciliferous band in cytoplasm, showing radiations 
from outer surface. (> 350 diam.) 
Fig. 42. Median section of two spermatids where ciliferous band has made asingle 
turn around the cell, showing band in section appressed against the plasma membrane 
on opposite sides of the nucleus. (X 350 diam.) 
Fig. 43. Tangential surface section of a spermatid, showing surface of band when 
it had madea single turn. (> 350 diam.) 
Fig. 44. Formation of double plasma membrane in the division of the central cell. 
(xX 1,800 diam.) 
Fig. 45. Mature spermatozoids in median section, showing nuclei, ciliferous band, 
etc. (x 200 diam.) 
Fig. 46. Cross-section of apex of spermatozoid, showing attachment of cilia to band 
which lies immediately below the plasma membrane. (Xx 600 diam.) 
Fig. 47. Separation of spermatozoids under the influence of sugar solution: a, 
mature pollen tube just before motion began; b, c, and d, after the motion of the 
cilia had begun, showing stages in the gradual pulling apart of the spermatozoids. 
Fig. 48. Pollen tube in a median stage of growth, showing the tube nucleus near 
the distal end of the tube. ( 75 diam.) 
Figs. 49 and 50. Pollen tubes, showing different shapes assumed by the tubes in the 
course of the growth of the proximal end, just preceding fecundation. (X 75 diam.) 
Fig. 51. Apex of nucellus, showing the proximal ends of the pollen tubes hanging 
down in the archegonial chamber shortly before fecundation. The tube nuclei have 
returned and taken position near the prothallus. (X 75 diam.) 
5526—No. 2—01——7 97 
