TYPICAL FORMS OF PLANT KINGDOM 99 



small one. This is the beginning of sexual reproduction, and we 

 call the large zoospore female, the small one male. The first 

 is sometimes known as an oosphere, and the second as an 

 antherozoid. In the seaweeds the oosphere is enormous and 

 immobile ; the antherozoid alone is active ; there are no 

 zoospores — reproduction is always sexual. Finally, in certain 

 Algae, the zoospores are replaced by immobile asexual 

 cells called spores, formed in special organs known as sporangia. 

 In the case of the Mosses these two kinds of reproduction are 

 combined, and alternate with perfect regularity. In the early 

 spring each small moss-stem expands at its extremity into 

 a delicate rosette of leaves, among which two kinds of minute 

 cups can be distinguished. The first, known as archegonia, 

 contain the immobile oosphere, and the second, known as 

 antheridia, are filled with very active antherozoids. Each 

 oosphere is soon fecundated by an antherozoid. Without 

 leaving its archegonium it develops into a small new plant 

 made up exclusively of a filament ending in an ovoid capsule 

 or sporangium, filled with spores. These spores, scattered over 

 the humid soil, develop into filaments similar to those of 

 the Confervas ; upon these grow the buds, which eventually 

 become new Moss plants. 



The method of reproduction found in the Mosses is retained in 

 those plants, frequently large in size, which belong to the three 

 classes of Ferns, Club-mosses, and Horse-tails, and together form 

 the division of the vascular Cryptogams. Here the method of 

 growth becomes complicated. The body of the plant generally 

 consists of a stem which creeps along the surface or under the 

 ground, at times almost indefinitely, and which is called a 

 rhizome. On this rhizome two kinds of ramifications grow in 

 opposite directions ; one sort moves upward towards the light and 

 forms leaves, and the other, pushing deeper into the ground, 

 forms roots — which here make their first appearance. Through 

 files of elongated cells, ranged end to end in a straight line, water 

 charged with salts absorbed from the soil finds its way upward 

 to the leaves, where it becomes charged with the sugar they 

 have formed, and makes its way back again to the roots. 

 This circulating water is the sap, and the long lines of cells 

 which provide its paths represent the vascular system of the 

 plant, an arrangement which is also here observed for the first 

 time, and which has earned for the Ferns, Club-mosses, and 



