i iii i a i a rh a i ai a 
1897 | LIFE HISTORY OF LILIUM PHILADELPHICUM 429 
stained alike. In fig. 20 one of the cells contains two nuclei 
which seem to represent generative and tube nuclei, and two 
‘other such cases were observed. In these cases, also, I am 
inclined to regard one of the cells as prothallial, and the other 
antheridial. 
EXPLANATION OF PLATES XXXV-XXXVI. 
All figures, except fg. 1a, were drawn with an Abbe camera lucida, +} 
Bausch and Lomb immersion, and Zeiss ocular 4. The combination gives 
a magnification of ro1o diameters. Fig. 7a was drawn with 4; Bausch and 
Lomb, ocular 18 Zeiss. The drawings are reduced one-half by photography : 
& Senerative nucleus, fr, prothallial cell. Figs. 3,9, zo are from L. auratum, 
all others from L. tigrinum. 
Fig. 1. Mother cell of pollen grain; the ribbon splitting longitudinally. 
Fic. ta. Small portion of ribbon showing usual shape and position of 
chromatin granules. Cyanin and erythrosin. 
PiG..2. Young pollen grain from tetrad, showing centrosomes and spiral 
arrangement of ribbon. 
Fic. 3. Mature pollen grain with two tube nuclei and two generative 
nuclei; one of the tube nuclei suggests direct division. 
Fic. 4. Division of primary nucleus of the pollen grain. 
Fic. 5. Generative nucleus accompanied by centrosomes; starch quite 
conspicuous. 
Fic. 6. Very common position of generative cell. 
Fig. 7. Less common position of generative cell. 
Fig. 8. Generative nucleus divided. 
Fig. 9. Generative nuclei divided ; one generative nucleus and the tube 
nucleus accompanied by centrosomes. 7 
Fig. 10, Three generative nuclei. 
Fic. 11. Tube nucleus divided. pees 
Fig. 12. Four nuclei, all with characters of _ nucle co i ; x 
- Fic. 13. Three nuclei, two of which indi ect division eee , 
Fic. 14. Two tube nuclei and one generative uackice: or the tube 
- nuclei shows direct division. 
© Figo is. Six tube nuclei and two generative r nuclei. ee 
ties 16. One tube eaemeseie. two. > generative uncles, and a p otha 
