440 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



of what appears to be coagulated cytoplasm. The struc- 

 ture of the pit will he referred to again, when discussing 

 the histology of the shoot subsequently. 



Connected with the central elongated cells of the con- 

 ducting tissue are the Collecting Cells. These are much 

 shorter than the central cells, and as we pass further out 

 they diminish still more in size. They form a rather 

 closer tissue than the conducting cells, and they are 

 extensively connected by pits, with or without the above- 

 mentioned protoplasmic caps, with any of the neighbour- 

 ing cells they may come into contact with. The nearer 

 we come to the outside the more regularly do they come 

 to lie in rows. Finally there arise from them the very 

 regular rows of Assimilating Cells, which run parallel to 

 one another, but are curved upwards and outwards at a 

 certain very definite angle with regard to the longitudinal 

 axis of the whole shoot. The assimilating cells possess 

 numerous pits, which are however all destitute of caps. 



The whole body of Chondrus crisjms consists of a com- 

 plete system of very long and very much branched hyphse. 

 The assimilating cells form the apical branches of these 

 hyphae. As a general rule the divisions in these threads 

 will take place at right angles to the longitudinal axis 

 of each cell row. But there is evidence to show that some 

 of the divisions are more or less at right angles to this 

 direction. Hyphal tissue of this kind has been distinguished 

 as plectenchyma. The filamentous nature of the tissues 

 becomes very apparent if the growing point of a frond is 

 examined in a longitudinal section, when one can see 

 spreading out in a fan-shaped fashion the hyphse of all the 

 three tissues (PI. II., fig. 6). 



In transverse section the cells of a young plant differ 

 little in appearance from what is seen in longitudinal 

 section, except that the conducting cells appear rather 



