132 MYCETOZOA. 



wall breaks in the course of a few hours, and an amoeboid body 

 issues as a distinct individual organism ; it soon assumes a some- 

 what pear-shaped form with a long cilium projecting from the 

 narrow end. This living body has received the name of " swarm 

 cell" from the German word, which would perhaps be more 

 correctly translated "roving cell," but as it has been generally 

 adopted for a large number of similar forms we must be content 

 with it. Immediately behind the cilium is situated the nucleus ; 

 what the function of the nucleus may be is very difficult to say, 

 if indeed it is at all known, but it evidently has an important office 

 to discharge; behind the nucleus lies the granular protoplasmic 

 substance of the swarm cell with one or more contracting vacuoles 

 such as are common to a whole host of Infusoria. The creature, 

 now free from the spore, swims away with a lashing movement of 

 the cilium or creeps over the slide of the microscope with the 

 cilium stretched out in advance. After some length of time the 

 cilium is withdrawn and the swarm cell takes a globular form, a 

 constriction is soon seen to occur, which increases until the cell 

 divides in two ; in a few minutes both halves assume the shape of 

 the parent cell, which they resemble in every respect except in the 

 size ; this they soon acquire, and they again divide, and so on for 

 a series of such divisions. 



At length this process ceases ; the cilia are withdrawn and the 

 swarm cells, which have now vastly increased in numbers, take the 

 form of amoebae with the movements characteristic of those 

 organisms. And now these amoeboid bodies coalesce when they 

 come in contact with each other and form centres, which are points 

 of attraction to surrounding swarm cells which congregate round 

 them and gradually unite to form a mass of naked protoplasm, 

 which has received the name of plasmodium. It is seen that in 

 the coalescence of the swarm cells the nuclei remain distinct : they 

 do not merge into each other as is the case in the conjugation of 



The plasmodium crawls in the substance of rotten wood or 

 among dead leaves or spreads over and feeds upon woody fungi 



