EUPHYCOPHYTA 217 



generally uninucleate but in some species a multinucleate condition 

 is found: this is climaxed in Griffithsia where each cell contains 

 several thousand nuclei. The cell wall is double, the inner wall 

 consisting of cellulose and the outer of pectic materials. Except for 

 most members of the first subdivision (the Protoflorideae) the cells 

 remain united to each other by means of thin protoplasmic threads 

 or plasmodesmae, which may be very conspicuous in the region of 

 the fusion cell (cf. below), where their thickness can perhaps be 

 associated with the need for the transmission of nutritive material. 

 So far it has not been possible to establish with certainty that the 

 protoplasmic strands actually penetrate the cell walls. Some species 

 contain special small vesicular cells rich in iodine, but the function 

 of these cells is not known. Iridescence caused by special bodies 

 within the cells is a feature of a few species, e.g. Chylocladia reflexay 

 Chondria coerulescens. 



The reproductive bodies are very characteristic, usually being 

 found on separate plants, but the two sex organs may occur on the 

 same plant, and certain abnormal cases are also known where sexual 

 and asexual organs are present on the same thallus (see p. 256). 

 The sexual plants are usually identical, but in Martensia fragilis 

 and Caloglossa leprieurii the male plants are smaller than the female. 

 The male organs, which are probably best termed antheridia al- 

 though they have been given other names, each give rise to a non- 

 motile body, or spermatiuniy which is carried by the water to the 

 elongated tip (trichogyne) of the carpogonium or female organ. In 

 this respect it will be seen that the Rhodophyceae are very distinct 

 from the other algal groups. 



The carpogonium with its trichogyne is usually borne on a 

 special lateral branch (except in the GeHdiales) which consists of a 

 varying number of cells, the parent mother cell being known as the 

 support cell. Often associated with this branch, or in some cases 

 forming a part of it, is a special cell, the auxiliary cell, into which 

 the fertihzed carpogonial nucleus passes. The carpogonial branch 

 plus the associated auxihary cell or cells is termed the procarp. 

 Apart from receiving the fertilized nucleus, in some of the more 

 primitive genera the auxiliary cell may also have a nutritive func- 

 tion. Some workers argue that such cells are not truly auxihary 

 cells and indeed cannot be strictly auxihary cells unless receiving 

 the fertihzed carpogonial nucleus. This view may seem to be too 

 extreme because it is evident that in these primitive genera we are 



