134 From Matter to Man. 



between the mineral and vegetal kingdoms, for a 

 coating of calcareous matter conceals their cellulose 

 tissue. In some algae the cells contain not only 

 vacuoles — cavities containing cell-sap (water with 

 various substances in solution) — but pulsating or con- 

 tractile vacuoles, common also to the amceba — virtu- 

 ally the stomachs of the cells. These phenomena 

 still further indicate the close relationship subsisting 

 between vegetals and animals. 



One of the simplest of algae is the minute red snow 

 plant {protococcus) whose whole organism consists of a 

 single cell. Root, stem, and leaves in one, it absorbs 

 nourishment through its cell wall. As the cells often 

 adhere in a viscous mass, they probably reproduce 

 by conjugation ; or perhaps, like amoebae they con- 

 tain within themselves the discordant elements of 

 their own disunion. In any case, they multiply by cell- 

 division, the cell splitting up into four parts, each with a 

 nucleus, and each eventually becoming a full-grown 

 plant. Lichens have recently been shown to be a 

 combination of two plants, algae and fungi, bound 

 together in intimate union. 



(3) To leave the cryptogams and enter the higher 

 sub-kingdom of phanerogams, 'we are attracted by the 

 climbing plants, of which there are many kinds. 



Climbing plants may be classified under five 

 heads : — 



(a) Rootlet climbers ; (b) hook climbers ; (c) stem 

 climbers ; (d) leaf climbers ; (e) tendril climbers. 



(a) The rootlet climbers are the ivy and a kind of 



