INTRODUCTION 



and creep with slow amoeboid movement. When two of 

 them come in contact with each other they may coalesce ; 

 others congregate at this point and a centre is formed to which 

 great numbers converge, and though they may remain distinct 

 for some time, they ultimately unite and mingle into one 

 moving mass, the plasmodium of Cienkowski (fig. 3). The 

 young plasmodia appear to exercise a definitely attracting 

 influence on the swarm-cells in their neighbourhood. Although 

 the fusing swarm-cells thus lose their individuality, their 

 nuclei, so far as has been observed, remain distinct. For 

 example, eight swarm-cells were counted uniting and forming 

 a plasmodium, and 

 their eight nuclei 

 could be afterwards 

 distinguished ; but 

 when this number is 

 exceeded the move- 

 ments of the plas- 

 modium and the 

 inconspicuous nature 

 of the nuclei present 

 difficulties in the way 

 of their recognition, 

 Whatever reason 

 there may be from 

 general considera- 

 tions to regard this 

 fusion of individuals 

 as akin to conjuga- 

 tion, no fusion of 

 nuclei, which appears 

 to be an essential part 

 of that process, has 

 yet been observed. 



In the Exosporeae, 

 represented by the 

 single genus Ceratio- 

 myxa, the mature 

 spore is ellipsoid, and 

 consists of granular 



protoplasm containing four nuclei ; it is enclosed by a mem- 

 branous and colourless spore-wall. On placing the spores 

 in rain water, the membranous wall is seen almost immediately 

 to slip free from the protoplasmic contents, often with a sudden 

 jerk, and by this action may be removed to some distance 

 from the now naked spore, while it retains its original form as 

 an empty transparent sac. The naked spore remains from 



Fig. 4. — Ceratiomtxa frdticulosa Macbr. 



a. Spore. 



b. Spore-contents escaping from the spore-wall. 



c. to g. Successive stages in the division of the naked 



spore to eight. 

 h. Cluster of eight swarm-cells. 

 Magnified 1200 times. 



