153 COMPARATIVE ANATOMY 



and if kept dry retain their vitality for an almost indefinite 

 time. But if they are wetted the spore coats are ruptured, and 

 their contents emerge as a number of pellucid globules, which 

 lie quiescent for a few minutes and then begin to put forth 

 pseudopodia and exhibit amoeboid movements. A few minutes 

 more and each animalcule becomes pear-shaped, develops a 

 contractile vacuole, a single flagellum at its narrow end, and 

 swims off with a dancing movement, the flagellum at the 

 narrow end being in advance, whilst pseudopodial processes 

 are given off from the broad posterior end. These active 

 bodies are known as flagellulse, and they feed actively on 

 living bacteria caught by the pseudopodia at the hinder end. 

 The flagellute, if well fed, multiply rapidly by binary division, 

 but after a time they become sluggish in movement, withdraw 

 their flagella, and creep about by their pseudopodia. In this 

 condition they are known as amoebulae. When two amoebulse 

 come into contact they coalesce, the protoplasm of the two 

 running together, whilst the nuclei remain separate. Other 

 amcebulse are attracted to the spot, often in great numbers, and 

 after a time the cytoplasm of all becomes confluent, and a new 

 Plasmodium is formed. It should be noticed that the union 

 of the amcebulae to form a Plasmodium is not a case of 

 conjugation ; there is no union of nuclei but only of cyto- 

 plasm, whereas conjugation consists essentially in the union 

 of nuclear matter from two different cells. Such a mass as 

 the Plasmodium of Badhamia, formed by the secondary fusion 

 of a number of cells originally separate, is often called a 

 syncytium, and it differs in its mode of origin, if not in its 

 ultimate constitution, from such a body as Actinosphserium, 

 whose many nuclei are the result of continued division of the 

 originally single nucleus without corresponding division of the 

 cytoplasm. But in Badhamia also, as soon as the Plasmodium 

 is formed the nuclei begin to multiply rapidly, so that the 

 distinction between syncytium and coenocytium breaks down. 

 Badhamia is a member of a large class of organisms which 

 live on decaying organic substances. It alone, in the plas- 

 modial condition, feeds upon living fungi, though the flagellulae 

 of a large number of species have been observed to feed on 

 living bacteria. Now, the ingestion of solid organic substances 

 and their digestion within the body are essentially animal 

 characteristics, and seem to justify the claim of zoologists to 



Digitized by Microsoft® 



