SECT. I 



CRYPTOGAMS 



345 



give rise to the numerous spores, whicli are set free by the disorganisation of tlie 

 l)lant. Aeeonliug to Pkowazek the plasniodium first divides into uninucleate 

 cells Avhich then conjugate in pairs to give rise to the spores ; the nuclei before 

 the fusion have undergone a reduction division. The spores germinate like those 

 of Chondriodcrma, and the nij'xamoebae penetrate the roots of a 3'oung Cabbage- 

 plant. The formation of true sporangia, however, does not take place, and this 

 Slime-Fungus rejiresents a more simply organised or, in consequence of its parasitic 

 mode of life, a degenerate ilyxomycete. 



According to the observations of Pinoy various Myxomycetes, among them 

 Plasmodio'phoru, only develop in the presence of definite Bacteria, which serve as 

 food for the Myxomycete Q^). 



Class V 

 Peridineae (^' ^'') 



The Peridineae or Dinoflagellata are connected as an indejiendent and further 

 developed group with certain Flagellata (Cryptomonadinae). They occur as 

 unicellular, free-swimming organisms in fresh water, but for the most part in the 

 sea, where, together with the Diatorneae, they constitute an important constituent 

 of the phyto-plankton. Tiieir 

 cells are characterised by the 

 possession of two long cilia or 

 flagella which spring from the 

 middle of the ventral surface 

 in a longitudinal furrow : one 

 of the cilia is directed back- 

 wards, the other is thrown 

 into curves and lies in a trans- 

 verse furrow (Fig. 258, A, gf). 

 The protoplast contains a 

 nucleus, vacuoles of different 

 sorts, and numerous brownish- 

 yellow chromatophores ; the 

 latter contain a mixture of 

 several special pigments (red- 

 dish-brown phycopyrrin, red 

 peridinin, and yellowish-green 

 chlorophyllin). Oil is usually 

 formed as the product of as- 

 similation. "While the Gymnodineae (Fig, 258, A) have either naked cells or cells 

 limited by a uniformly thickened cellulose wall, the typical Peridineae have a 

 wall composed of cellulose formed of polygonal plates ; these are usually delicately 

 sculptured and perforated with pores. The transverse furrow is formed by one 

 girdle-shaped plate. 



In many Peridineae of the plankton the plates bear special wing- like 

 expansions (Fig. 259) or the cells have long horn-like processes. These adapta- 

 tions enable the organisms to remain floating in the water {^^). 



In some Peridineae the chromatophores are only represented by colourless 

 leucoplasts. Such species liv •• either as saprophytes or in the same way as 

 animals. Gymnodinium hyalinum is a colourless, naked, fresh-water form, the 



Fic. 2-08. — A, Gymnodinium rlmmhoides : If, loiigitiHUnal 

 groove ; gf, transverse groove. B, Peridinium talndatum : 

 h, waO. {A, After Schutt ; li, after Klebs ; from Olt- 

 MANNS' Algae.) 



