FERTILISATION OK FECUNDATION. 265 



stamens in the very early state of the flower, before the pollen is 

 perfectly formed, prevents fertilisation. Care must be taken, in all 

 such experiments, that pollen is not. wafted by the wind or carried 

 by insects to the pistil from other plants in the neighbourhood, and 

 the result must be put to the test by the germination of the seed. In 

 some instances the fruit enlarges independently of the application of 

 the pollen, without, however, containing perfect seed. Thus, a species of 

 Carica was fertilised by the application of pollen, and produced perfect 

 fruit and seed, and it continued for at least one year afterwards to 

 have large and apparently perfect fruit, but the ovules were abortive. 



Some authors maintain that in the case of Hemp, Spinach, 

 Lychnis dioica, Coelebogyne ilieifolia, Aberia Caffra, and some other 

 plants, perfect seeds have been produced without the influence of 

 pollen, but these statements have not been confirmed. Such cases 

 are recorded as examples of Parthenogenesis ("ira^Sivog, maiden, ymaig, 

 origin), or the production of perfect seeds without fertilisation. In 

 Phanerogamous or flowering plants all experiments lead to the con- 

 clusion that there are distinct sexual organs, the presence of which is 

 required for the production of the embryo. 



In Cryptogamous or flowerless plants there are also organs of re- 

 production, although they are not always very conspicuous. In the 

 simplest form of Cryptogamic plants, reproduction and nutrition 

 progress within the same cell. As we ascend in the scale of vegeta- 

 tion, and the plant becomes more complex, there are cells of diiferent 

 kinds, which require to be brought into contact in order "that spores 

 (which are equivalent to seeds) may be produced. These reproductive 

 cells are of two kinds, and they are situated either together or apart, 

 on the same or on diiferent individuals, one Fig. 467. Fig. 468. 



representing the male and the other the female. 

 One of these is the Antheridivmi (avSrighg, 

 flowery, eldog, form), a cellular body, containing 

 free cells, in which are enclosed Phytozoa ((purbv, 

 a plant, and ^tmk, living), (Antherozoids), minute 

 bodies which exhibit movements ; the other is 

 the Pistillidium or Archegonium (ag;^)], begin- 

 ning, and yovog, offspring), containing cells 

 which, after contact with phytozoa, are able to 

 germinate, and which are sometimes provided ■^'^' *'*• *'s- 47o. 

 with cUia (flgs. 467-470), and then are called Zoospores (^wis; living 

 and ffwoja, a seed or spore), or moving spores. The phytozoa are re- 

 garded as exercising a function similar to that of the spermatozoa in 

 animals, and hence they are sometimes called Spermatogoids (c'Trsma 



Figs. 407-470. Spores of different fresh-water Algffl. Fig. 467. Sporesof Conferva, with 

 two vibratile cilia. Fig. 468. Spore of Chatophora, with four cilia. Fig. 469. Spore of 

 Prolifera, with a circle of cilia. Fig. 470. Spore of Vaucheria, covered with cilia. 



