74 



FIRST GROUP. THALLOPHYTES. 



conjugate with the trichogyne, and their protoplasmic contents pass into it. The tri- 

 chogyne itself is not excited by this union to further development, but it is first cut off 

 from the carpogone by a transverse wall and then disappears. The carpogone, 

 on the other hand, in consequence of the fertilisation puts out a number of 

 shoots, which divide transversely and form cells, each of which is a carpospore and 

 may germinate at once. The process of fertilisation is still more simple in the 

 genera Bangia and Porphyra, as will be subsequently explained. With regard to 

 the details of the process there is much yet to be learnt. In Nemalion and its allies 

 the nucleus of the procarp-cell lies perhaps at first in the trichogyne, where it unites 

 with the nucleus of the spermatium, and then passes downwards into the carpogone - 

 portion. Where the trichogyne and carpogone are separated from the first by a trans- 

 verse septum, the process must be complicated ; but here too we must assume that the 

 substance of the spermatium, which is first taken up by the trichogyne, is then con- 

 ducted to the carpogenous cells. 



FIG. 46. Young thallus of Melobesia Lejolisii formed on the ellipsoidal germ-disk beneath. The periclinal walls are 

 omitted in the portion of the figure to the right. After Rosanoff and Sachs. 



The species in the group of the Florideae are extraordinarily numerous, and 

 with some exceptions (Batrachospermum, Lemanea, Thorea, some species of Chan- 

 trasia, Bangia and Hildebrandtia) belong to the sea. In the living state they are 

 usually of a red or violet colour, sometimes of a dirty green or biackish hue, as 

 Balrachospermum. The green colour of the chlorophyll-corpuscle is masked by a 

 red pigment 1 ; but the absorption-spectrum of an alcoholic extract of -chlorophyll 

 from the Florideae is not quite the same as in phanerogamous plants. The red 

 colouring matter is soluble in cold water ; it is carmine-red in transmitted light, red- 

 dish yellow in reflected light (with a tinge of green in Rythiploed] ; the chlorophyll- 

 corpuscles also show this fluorescence when the red colouring matter (phycoerythriri) 



1 Rosanoff in Comptes rendus, April 9, 1866. Askenasy in Bot. Zeit. 1867. Pringsheim, Ueber 

 nat. Chlorophyllmodificationen u. d. Farbstoffe d. Florideen (Monatsber. d. Berl. Akad. Dec. 



1876). 



