THE SIMPLER ORGANISMS 



103 



sporangia with them. These threads, formed from residua] 

 shreds of the plasmodium, are very hydroscopic, and when 

 they dry out, twist and turn vigorously, scattering the 

 spores. When favoring wind or water bears a spore to a 

 favorable place for germination, it bursts its cell wall and 

 there creeps out therefrom a minute, naked amoeboid cell, 

 which moves about for a time by means of pseudopodia. 

 Then it develops a long lash at one end of the body (fig. 60) 

 with the aid of which it swims for a season. Then it settles 

 down, in company with others of like kind, and with the 

 others fuses into a plasmodium of minute size, which has 

 only to absorb food and grow to attain to the size and 

 character of that with which we started. 



Thus we see that from the time of germination of the spore 



=^ # U 



Fig. 60. Reproduction in slime molds, a, elater; b, spores; 

 c, one germinating spore and three amoeboid cells escaped 

 from other spores; d, the same cells a little later when free 

 swimming; e, convergence of these cells to form a Plasmo- 

 dium ; /, a small plasmodium. 



until the plasmodium is mature, the slime mold exhibits 

 the free locomotion and the feeding habits of the animal, 

 while thereafter it develops cellulose cell walls and pro- 

 duces spores like a plant. Nature has not always estab- 

 lished hard and fast boundaries, even between her major 

 groups of organism. 



Study 14. Observations on slime molds. 



Materials needed: living plasmodia, and mature spor- 

 angia of any common species. Both may be brought into 

 the laboratory on pieces of moist wood. The plasmodia, if 

 broken into fragments with the wood, and placed on slides 

 under a darkened bell jar, will in a few hours creep off the 



