266 



CRYPTOGAMIO EMBEYOGENY. 



seed). A cessation of their active movements has been observed co- 

 incident ■with the earliest formation of the embryo. When the 

 contents of the antheridia and archegonia are brought into contact, 

 a cellular body is produced in the latter. This cell or germ, when 

 mature, may either be discharged, or may remain in connection with 

 the plant until further developed. 



Fertilisation or Fecundation in Gryptogamous or Flowerless Plants. 



In the simplest Oryptogamic plants, composed of a single rounded 

 cell, as the Yeast plant, the Red-snow plant, and Palmella cruenta 

 (fig. 44, p. 14), the processes of reproduction and 

 nutrition cannot be separated. The same cell ap- 

 pears to perform both functions. At a certain 

 period of growth divisions take place in the ceU- 

 contents, and by the bursting of the parent cell 

 germs are discharged which are capable of produc- 

 ing new individuals. As we ascend in the scale the 

 plants become more complex. In place of one cell 

 ^ they consist of several, united together either in a 

 single or branched linear series, and combined both 

 end to end and laterally, so as to form cellular ex- 

 pansions. In this state the nutritive and reproduc- 

 tive cells are often separate and distinct, as may be 

 seen in common Mould, and in Fungi generally. In 

 Confervse (fig. 45, p. 14), and in Diatomaceae (fig. 

 472), reproductive cells are observed with distinct 

 functions. In many of them we perceive at certain 

 stages of growth cells uniting by a process of conju- 

 gation, the result of this imion being the pro- 

 duction of a cellular embryo or spore. This conjugation is a very 

 interesting process, and tends to throw light on the subject of 

 reproduction throughout the whole vegetable kingdom. It is well 

 seen in species of Zygnema, Spirogyra, Tyndaridea, Mougeotia, and 

 Staurospermum, which are called Conjugate on this account. The 

 cells in these plants have in their interior a granular endochrome, 

 which appears to have difierent functions in the different cells. When 

 certain cells are brought into contact, tubes are emitted which unite 

 the two (fig. 471 6), the endochromes come into contact and the 

 result is the formation of a spore, the mixed endochromes being 

 surrounded with a proper membrane. Sometimes the contents of 



Fig. 471. Filaments of Zyguema, with conjugating cells. The tubes uniting two cells 

 are seen at &, and similar tubes connect two upper cells, a and d. The contents of the cells 

 intermingle, and spores or sporoid embryos, c and d, are produced. The upper cells, in 

 which there is no conjugation, retain their usual contents ; while some of the lower cellS' 

 have lost their contents, and spores are produced in others. 



