172 Plant Biology 



this rapid reproduction does not occur in nature because of limited food 

 supplies, the production of poisonous wastes, etc. 



Another asexual method of reproduction possessed by certain species, 

 primarily rods, is by the production of resistant endospores. When a 

 spore is formed, the cell condenses its protoplasm into a spherical or oval 

 mass which is quite resjstant to external conditions. This mass forms 

 the spore with its protective spore wall and its relatively low water con- 

 tent. When proper environmental conditions are encountered, the spore 

 germinates to form a new bacterial cell, which will divide by fission. 



A few species of bacteria produce within their cells a number of tiny 

 bodies called gonidia (go -nid' i a) (Gr. gone, "seed"; idion, small), each 

 of which develops into a typical bacterial cell. Certain species, especially 

 the filamentous types, may produce tiny conidia (ko-nid'ia) (Gr. konis, 

 dust; idion, small) at the tips of the filaments, similar to the formation 

 of such structures by certain true fungi. 



SLIME MOLDS (PHYLUM MYXOMYCOPHYTA) 



There are about 300 species of slime molds (slime fungi), most of 

 which are saprophytes on damp, decaying vegetable matter. They re- 

 semble certain fungi in their methods of spore formation and resemble 

 certain lower animals by their slimy, amoeba-like bodies, their amoeboid 

 methods of locomotion, and their ingestion of solid foods. Although the 

 methods of reproduction and the physiologic activities vary with the 

 species, the following general description is rather common and typical. 



The vegetative body is a thin mass of slimy, naked, viscous protoplasm 

 known as the Plasmodium (plaz -mo' di um) (Gr. plasm,a, liquid; eidos, 

 form). The plasmodium contains many nuclei and creeps by a flowing 

 amoeboid motion through the formation of pseudo podia (su do -po' di a) 

 (Gr. pseudes, false; pous, foot). It may ingest solid foods in a manner 

 similar to that employed by certain lower animals (Fig. 35). 



After a period of amoeboid locomotion the plasmodium produces a 

 number of spore cases known as sporangia (spor -anj' i a) (Gr. sporos, 

 seed; anggeion, vessel) . The sporangia vary in size and form, depending 

 on the species, and are used in classifying slime molds. Sporangia may 

 be colorless, purple, orange, brown, etc. As a sporangium matures, the 

 internal protoplasm forms a network of delicate fibers known as the 

 capillitium (kap i -lit' i um) (L. capillus, hair), in the meshes of which 

 are formed numerous unicellular, nonmotile spores (Fig. 35). 



The liberated spores germinate, each producing one to four swarm cells 

 or myxamoebae (mik sa -me' ba) (Gr. myxa, slime; amoibe, change) and 



