250 CRYPTOGAMS AND PHANEROGAMS. 



mother-plant, it spends a longer or shorter resting period as the 

 embryo in the seed (enveloped by the testa), and does not make its 

 appearance nntil the "germination " of the seed. In addition the 

 shoot which bears sporangia undergoes greater modification than 

 in the case of the Flowerless-plants. 



The Phanerogams are separated into two Divisions as follows : 

 Division 4. Gymnospermae. The ovules, as well as the seeds, 

 are borne naked on the surface of open carpels, or on the apex of 

 a stem (ovary wanting). The pollen-grains are conveyed by the 

 wind to the ovules, and caught by drops of mucilage, secreted by 

 the micropyle. A "stigma" is wanting. The entire female prothal- 

 lium, (the endosperm}, which serves for the nourishment of the 

 embryo, is formed before fertilisation. The archegonia are em- 

 bedded in the upper part of the prothallium. The pollen-grains ar. 

 " multicellular" i.e. there is always in their interior a distinct 

 prothallium, formed by 1-3 cells, and a larger cell which gives 

 rise to the pollen-tube. 



Division 5. Angiospermse. The carpels surround the ovules 

 and form an entirely closed chamber (ovary), in which the ovules 

 mature and ripen into seeds. The surface of a portion of the 

 apex of the carpel is transformed into the " stigma," which, by a 

 sticky fluid and also by hair- structures, is capable of retaining the 

 pollen-grains conveyed to it by the wind, or more frequently by 

 insects. The pollen-tube grows from the stigma, through the 

 "conducting cellular tissue" (style), to the ovules. The pollen- 

 grains contain two cells, a vegetative and a free generative cell. 

 The latter passes into the pollen-tube and there divides into two, 

 one of which is the sperm-nucleus. The female prothallium, 

 which is intended to serve as nutritive-tissue, is formed after 

 fertilisation. Archegonia are wanting. 



