€S THE AUSTRALIAN NATURALIST. 
chief of which is the manufacture of food or Photosynthesis, 
this first food being a carbohydrate such as starch or sugar, and 
this carbohydrate food with stored energy is the foundation for 
all the other foods made, and hence for the building up of and 
repairing of plant cells and tissues. 
Thus a plant strives to get the best position for Lght suit- 
able to itself, and in doing so very gradually evolves more com- 
plex tissues, which are necessary for erect positions, ete. 
A more elongate type of thallus is evolved with the strength- 
ening up of groups of cells, etc., and so tissues are formed, often 
with specialised cells. 
Phyllospora belongs to the group of sea weeds called Phaeo- 
phyceae or brown plants, the colour being due either to a pig- 
ment which masks the green chlorophyll or to one pigment called 
“shacophyll,” which is similar in function to chlorophyll, and is 
easily converted into it. (Molisch). 
I placed segments of the thallus of Phyllospora in weak 
solution of formalin, and got a brownish solution after a day. 
The same segments were then placed in 70 % alcohol, and the 
clear green colour was shown in the solution after standing’ an 
hour. ; 
Microscopic Work. Section thallus (Plate II. Fig. 1.) 
The section of a leaf-like branch of the thallus showed three 
well marked zones. (1) Cortex. (Plate Il. Fig. 1. a.), with 
pigmented cells where photosynthesis take place. The outer- 
most row of such cells are palisade-like, and are followed by 
small rounded cells which gradually get larger and paler in 
colour till they merge into (2), the Medulla (Wig. 1. b.), a 
colourless area with large cells forming a padding-tissue for (3) 
Conceptacles (Fig. 1. ¢.); the medulla also is a. conduction and 
storage tissue for foods. (4). Mid-rib tissue: (Fig. 1. d.) 
there is a distinctly marked band of thickened small cells with 
thick gelatinous swollen walls and small lumen. Nearly all the 
cell walls have a swollen appearance. A mucilaginous sheath 
seems to cover the branches of the plant which gives the branches 
a smooth surface and allows free, easy moyement of segments 
over each other in the waves. 
The Fruiting “leaves” (Plate I. Fig. 4). On certain leaf- 
like branches of the Alga, a series of elongate elliptical swellings 
can be seen, and if a lens be used, a little opening or ostiole 
(Plate I. Fig. 3. a.) can be seen. This opening leads into a 
flask-shaped cavity (in cross section) which is embedded in the 
general tissue. This cavity is called a Conceptacle or Scaphidium. 
