EMBRYO 209 



1. The campylotropous ovules, with curved body. 



2. Pollen-tubes, which are often to be found with 

 the end applied closely to the micropyle. 



Similar observations may also be made on Stellaria 

 media, and many other plants. 



Strasburger observed the process of fertilization itself directly 

 in Torenia asiatica. Gloxinia, and also in Orchids, Monotropa, and 

 Pyrola. His method was to open the ovary of a flower a short 

 time after pollination, and detach and mount the ovules in a 

 3 per cent, solution of sugar. 



RESULTS OF FERTILIZATION. 



A. DEVELOPMENT OF THE EMBRYO. 



i. Dicotyledon. 



Pick out the ovules from a fresh ovary of Capsella 

 Bursa-pastoris, which has attained about half the ultimate 

 size of the mature fruit : material kept in spirit will 

 not do well for this work. Treat with dilute potash, 

 and examine with a low power. Observe 



1. The form of the ovule (campylotropous, i.e. 

 with a curvature of the body of the ovule). 



2. The funiculus, or stalk. 



3. The integuments. 



4. The micropyle, not very easily seen : a pollen- 

 tube may often be observed entering the micropyle. 



5. A large central cavity (the embryo-sac), which 

 is curved like the whole ovule. In this may be seen, 

 more or less distinctly 



6. The embryo. 



To study the structure of the embryo, either longitu- 

 dinal sections of the ovule must be cut, and the embryo 



