F. Børgesen: Rhodopliyceæ of the Danish W. Indies. 



363 



The tetrasporangia, antheridia and cystocarps are found upon 

 separate plants. 



The tetrasporangia are developed in the peripheral tissue. The 

 mother-cells of the sporangia become enlarged, filled with proto- 

 plasma and getting a dark red colour. They are zonately divided. 



The antheridial 

 stands occur every- 

 where upon the sur- 

 face of the male plants 

 forming smaller or larg- 

 er groups. 



The procarps and 

 carpogonial branches 

 are formed on the inner 

 side of the peripheral tis- 

 sue facing the cavity in 

 the thallus. We will 

 therefore begin to ex- 

 amine a section of this 

 tissue from the summit 

 of a female plant. Fig. 

 356 shows a part of 

 such a section; the in- 

 nerside of it, which is 

 facing the cavity of the 

 thallus, is turned up- 

 wards. To make the 

 organs of reproduction 

 more clearly visible I have coloured the tissue in hæmatoxylin. 



In the middle of the figure we find a short branch composed of 

 rather robust cells. It originates from one of the filaments found 

 on the innerside of the peripheral tissue, whose large cells are seen 

 underneath. This branch consists at first of a smaller oblong cell, 

 then follows a larger one having in this case an outgrowth on the 

 left side. The next cell is especially coloured by the hæmatoxylin 

 and filled to a great extent with granular cell contents; it has also 

 a thicker wall than the other cells of the branch. This cell is the 

 auxiliary cell. It always bears three cells. In the figure two of them 

 only are visible, the third one is lying underneath the auxiliary cell. 



Fig. 356. Agardhiella tenera (J. Ag.) Schmitz. 

 Part of the tissue seen from the innerside with 

 auxiliarv-cell branch and carpogonial branches. 

 (About 250:1). 



