588 



ORGANOGRAPHY. 



.^'T 







niatozoids of the higher cryptograms. They are sometimes 

 enclosed in spermagonia (^Fig. 827), like those of Lichens 

 (p. 384). The thread-like stalks upon which the spermatia are 



placed have been termed 

 Fig. 827. .sterigmata (Jig. 827 st). Al- 



though they have been sup- 

 posed to represent the male 

 organs, yet at present the 

 sexual nature of the Fungi is 

 not clearly ascertained. With 

 regard to the Fungi generally, 

 it may be observed that our 

 knowledge upon many points 

 is becoming enlarged every 

 day, so that much of what 

 may be written now will pro- 

 Iiably soon require modifica- 

 t ion. 



3. Alg^ or Sea-weeds. 

 — This group of plants, like 

 the Fungi, comprises a vast 

 number of species, which vary 

 exceedingly in form, colour, 

 size, and other peculiarities. 

 They are all either inhabitants 

 of salt or fresh water, and may 

 be microscopic plants, or growths of enormous length. They are 

 commonly divided into three orders, which are called respec- 

 tively, ChlorospermecB Chhrosporece or Confervoidece, Rhodo- 

 spermece Rhodosporece or Floridece and Melanospermece Mela- 

 nosporece or Fucoidece. The reproductive organs of each of these 

 orders will be very briefly described. 



1. Chlorosporea:, Corifervoidece, or Green-cohured Alga. — The 

 simplest plants of this group, as Protococcns (figs. 147 and 148), 

 &c., consist of a single cell, so that the nutritive and reproduc- 

 tive processes cannot be separated; but eacli cell has the i)ower 

 of dividing by the process of cell-division into two or four ucav 

 cells, from which new individuals are formed when the parent- 

 cell bursts. In other cases, as in Zi/gnema (fig. 828), the cells 

 of two filaments, c, d, unite by a lateral cellidar process, p, by 

 means of which their contents (endochrome) intermingle, and the 

 result is the formation of a spore, s, capable of germinating. 

 This process is called conjugation, and will be more particularly 

 explained hereafter. In other plants of thiS group the spore is 

 api)arently developed without conjugation. Besides these true 

 spores, which may be called resting or inactive spores, we have 

 also formed in the ])lants of this group, as in many other Alga;, 

 what have been called zoospores or gonidia (fig. 146). These are 



Fi(i- 827. ^cc^i()n oi a Fperm 

 Fungus. After Henfrey. i 

 St. Sterigmata. 



gonium of a 

 Spermatia. 



