188 LINNEAN SOCIETY OF LONDON. 
the old aes into the two distinct series of Fungi and 
ge. He believes arrest of development has had an eg 
influence in many peed deviations among the groups in 
- ques Retrogression may take the form of the suppression of 
ae “the muain or the reproductive organs, and wherever one 
of these se ~ of organs is suppressed at the expense of the other, 
retrogression may be prima facie assumed. e principle 
advocated iy the Yate holds good, it leads towards the almost 
abandoned division of the ews. pee the green, the red, and the 
brown,—Chlorosporee, Rhodosporee, and Pheosporea, Tt would 
appear as if at an early period in the development of the simplest 
form of vegetative life, three kinds of cell-contents were repre- 
sented, a colourless, a So eR and a pure green. thereon 
are the author’s three great divisions :— 1. Schizom pets, forms 
entirely destitute of Seecophyll, and adapted to carry on only a 
parasitic existence throococcacea, unicellular * oranges with 
cell-contents Saisces of watery blue-green endochrome diffused 
ough the protoplasm, without diatinet Shoe ae: -grains, starch- 
grains, or nucleus; III. Protococcacee, characterised by cells pos- 
sessing a nucleus, starch-grains, pure ¢ seen cat pages 5 with 
that of higher plants, and in certain states a cell-wall of 
cellulose. The (I.) oe ig lead to the Fungi Which are not 
discussed by the author. The (II 2. “4 ‘oococcaceé pass through the 
Gectltaetasas to Nostocacee. The (III.) Protococcacee are the great 
derivatives of the Algal group. Hence three great lines of descent | 
are bot wig (1) The Diatoms are regarded as of remote sac 
: (a) the Cintas edetieg Zygnemacee and Desmids ; 
(6) the brown seaweeds adapted to deep-sea life, Phwosporea, ter- 
mina in Fucacee; and (c) the Confer ine heterogama, at the 
extreme of which the Coleochatea are reached. The Coleochatea lead 
direct to the red seaweeds or Floridee, a natural group with great 
variety in development of the sexual organs. By arrest of develop- 
ment branches proceed on the one hand to the Nemalie«, on the 
other hand through the Bangiacee to the Ulvacea; while at a 
by a fungus belonians to the genus Padme a ato 
; _ 
a iby then them P, Bs eta ——, ns are 
ne being the abosbol scanaity 
of of badly affected p plants Teng wholly destroyed, 
