626 



ANGIOSPERMAE DICOTYLEDON ES 





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, z\ 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 375 /u. long and 30 p broad. 



FlG. 302. 1-7. Chrysanthemum segelum, 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. Anlhtmis arvensis, L. (8) Tip of the style of a disk-floret with diverging and strongly recurved 

 branches. 



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

 are seen. 



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



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



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

 3. Scatophaga merdaria Z. ; 4. Sepsis cynipsea Z. (6) Syrphidae : all skg. and 

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

 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 : 1 3. Vanessa io Z., skg. 



