II 



PHYLUM PROTOZOA 



49 



may exist either in the active or in the resting condition. In the resting stage 

 (B, a, b, c) it consists of a mass of protoplasm surrounded by a laminated wall 

 of cellulose and coloured green by chlorophyll the ordinary pigment of green 

 plants. There are also specks of bright red, due to a pigment called hcvmato- 

 chrome, allied to chlorophyll, and small globular bodies of a bluish tint. In 

 the young condition (a) the resting cells are globxilar and microscopic, lying 

 enclosed within the cells of the Sphagnum, but as they grow in this confined 

 space they become elongated and irregular, and finally Irarst through the Avail 

 of the moss-cell, forming masses (b, c) quite visible to the naked eye. These 

 may bud (C) or undergo binary fission (D) ; or the protoplasm, retreating from 

 the cell-wall, may divide into numerous small masses, each of which surrounds 

 itself with a new cell-wall (E). 



During the whole of the resting stage there is nothing to distinguish Chlamy 

 domyxa from a plant, and it would certainly be placed among the lower Algce 

 if the active phase of its existence were unknown. 



In the active stage (A) the protoplasm protrudes from the ruptured cell-wall 

 in the form of pseudopods produced into a complex network of extremely 

 delicate filaments, which may unite to form larger masses of protoplasm at a 

 considerable distance from the original cell. At the same time the bluish 

 spheres (.y). ) found in the resting stage take on a spindle shape and travel slowly 

 along the filaments. 



The filaments are used to capture living organisms (/.) which are digested by 

 the protoplasm surrounding them, the products of nutrition being conveyed 

 along the network to all parts of the organism. Thus in the active condition the 

 nutrition of Chlamydomyxa is holozoic, i.e. strictly like that of an animal, the 

 food consisting of living protoplasm. In the resting stage, on the other hand, 

 nutrition is purely holophytic, i.e. like that of an ordinary green plant, the food 

 consisting of the carbon dioxide and various mineral salts dissolved in the water. 



Labyrinthtila (Fig. 31) differs in many respects from Chlamydomyxa. In the 

 resting stage (B) it consists of a heap of small nucleated cells (c. ) connected by a 



B 



FIG. 31. Labyrinthula vitellina. A, specimen crawling on a fragment of Alga (.) ; c. cells 

 travelling in the filaments ; B, part of specimen in resting condition with heap of cells (c.) ; 

 C, a single cell from an actively moving specimen with connecting threads; an. nucleus. 

 (From Biitschli's Protozoa, after Cienkowsky.) 



homogeneous substance. In the active condition (A) it is produced into long 

 delicate filaments, not formed of protoplasm, along which the cells (c. ) travel, in 

 the same manner as the spindles of Chlamydomyxa. Labyrinthula has, therefore 



E 



