CHAPTER XXII. 

 THE REPRODUCTION OF ALG^E. 



PRINCIPAL MATERIALS USED. 



Spirogyra in conjugation ; fresh. Or, fixed with 1 per cent, chromic acid, 

 and preserved in water containing a little camphor. 



Cladophora glomerata ; fresh. 



Vaucheria sessilis, preferably from running water ; fresh ; or, if need be, the 

 terrestrial form. For swarm-spore formation, Cladophora or VaucJieria 

 should be collected a few days before wanted, and placed in flat saucers 

 with water ; sexual organs are produced in VaucJieria by cultivation for 

 a week in 2-5 per cent, sugar solution, and bright light. 



Fitcus platycarpus (or F. vesiculosus, male and female), fresh ; also in 

 alcohol. 



Cliara fragilis ; fresh. 



PRINCIPAL REAGENTS USED. 

 1 per cent, osmic acid Iodine Alum carmine Logwood. 



IN our morphological studies we have followed the plan of com- 

 mencing with the better-known highly-organised plants, and work- 

 ing downwards to those of the utmost simplicity. It is now our 

 purpose to study microscopically the processes of reproduction ; 

 and here we shall follow the reverse route, ascending from the 

 lowliest organisms to those of the highest degree of organisation. 

 We have already commenced this study, in our last chapter, upon 

 Bacteria and Yeast, to the entire cycle of development of which 

 we have directed our attention. In the whole of this life cycle 

 there was no indication of separate sexuality. The process of 

 multiplication was vegetative, or asexual. Organisms of some- 

 what higher grade, however, show both of these processes, 

 vegetative or asexual multiplication, on the one hand of entire 

 organisms, or on the other hand of the constituent cells of those 

 organisms, and the commencement of the life cycle of new indi- 

 viduals through more or less complicated processes of sexuality. 



(290) 



