AMOEBOID PROTOZOA (SARCODINA) 217 



and results from the transfusion of part of the chromatin through 

 the nuclear membrane or from the breaking up of the nucleus into 

 small granular bodies which become diffused through the cyto- 

 plasm. 



In some Sarcodina a number of buds may separate from the 

 parent, each enclosing a quantity of idiochromidia which is built 

 into a nucleus. This extranuclear material apparently has a 

 functional value in reproduction and may be compared to the 

 micronuclei of Infusoria. During the quiescent state of encyst- 

 ment the bodies of many Sarcodina break into swarm spores. 

 These are minute organisms each with a portion of the parent 

 nucleus and provided with fiagella or pseudopodia as motile organs. 

 The swarm spores may fuse with each other and develop into an 

 adult form or, in some cases, they may develop without fusion. 



Conjugation, in the form of a temporary union or a permanent 

 fusion of the bodies of two individuals of the same species, has 

 been observed in some Sarcodina. After temporary union and 

 separation, in a few cases, swarm spores have been observed to be 

 developed from both conjugants. 



In most of the instances of permanent conjugation reported 

 there is no clear evidence that the fusion resulted in a union of the 

 nuclei of the individuals, as is the case in true conjugation. Actual 

 fusion of the nuclei, however, has been observed in the common 

 ''sun animalcule," Actinophrys sol. Here two indi\iduals come 

 together, fuse, and become encysted. Nuclear changes take place 

 which follow in a general way the processes of maturation and 

 fertilization after which mitotic division results in the formation of 

 daughter cells. 



Many kinds of Sarcodina are exceedingly abundant and collect- 

 ing them is not a difficult matter. Other forms are rare and only 

 occasionally obtained. Everywhere among wet mosses and in 

 sphagnous swamps many fine examples of shell-bearing species 

 will be found, some inhabiting no other localities. Some prefer 

 clear, fresh water, while others thrive in stagnant ponds and ditches. 



By carefully collecting submerged decaying vegetation from shal- 

 low water and allowing it to stand in the laboratory for a few days 

 many of the Amoeba and Difflugia types arc usually found. 



