626 



ANGIOSPERMAE—DICOTYLEDONES 



almost I cm. There are about 300 disk-florets. Each of these is 6-7 mm. long, 

 of which 2 mm. is taken up by the ovary, 2^ by the corolla-tube, and 2 mm. by the 

 bell of the corolla. In the first stage of anthesis the apposed stylar branches, 

 covered with pollen, project from the bell; in the second stage the stigmatic 

 inner surfaces of these branches protrude slightly. The diameter of the spinose 

 pollen-grains is somewhat less than that of the median groove that traverses 

 the stigmatic surface. The stylar branches of the ray-florets bear shorter sweeping- 

 hairs than those of the disk-florets. It is noteworthy that in this species the 

 upper surface of the bell of the corolla in both kinds of floret is beset with 

 countless microscopic papillae. Should insect-visits fail the pollen falls automatically 

 on the expanded stigmatic surfaces. Warnstorf (Verh. bot. Ver., Berlin, xxxvii, 

 1896) describes the pollen-grains as yellow in colour, usually ellipsoidal, closely 

 spinose, on an average 37-5 /* long and 30 m broad. 



Fig. ao2. 1-7. Chrysanthemum segetunt^ L. (from nature), (i) Disk-floret in the first (male) 

 stage; pollen is issuing from the anther-cylinder. (a) Do. in the second (female) stage. (3) Female 



ray-floret. (4) Tip of the style of a disk-floret in the first (male) stage (with branches apposed), enlarged. 

 p^ stigmatic papillae. (5) Do. in the second (female) stage (with branches curving outwards), greatly 

 enlarged. (6) Tip of the style of a ray-floret with diverging branches, enlarged. (7) Tip of stylar 

 branch of a disk-floret, seen from within ; in the middle is a groove mixed with pollen-grains ; greatly 

 enlarged. 



8. Anthentis arvensis, L. (8) Tip of the style of a disk-floret with diverging and strongly recurve'd 

 branches. 



9. Tanacetum Parthenium^ L. (9) As 8, but branches much less divergent; a few pollen-grains 

 arc seen. 



10. Matricaria ChamorHilla, L. (10) As 8, but branches less divergent. 



Visitors. — I observed the following in the island of Fohr and at Kiel. — 



A. Diptera. (a) Muscidae: all skg. : i. Lucilia caesar Z. ; 2. L. comicina F. ; 

 3. Scatophaga merdaria Z. ; 4. Sepsis cynipsea Z. (3) Syrphidae : all skg. and 

 po-dvg. ; 5. Eristalis arbustorum Z. ; 6. E. nemorum Z. ; 7. E. tenax Z. ; 

 8. Helophilus pendulus Z. ; 9. Syritta pipiens Z. B. Hemiptera. Capsidae: 

 10. Calocoris roseomaculatus Deg.; 11. Lygus pabulinus Z. ; 12. L. pratensis F. 

 C. Lepidoptera. Rhopalocera : 13. Vanessa io Z., skg. 



