488 FISSION FUNGI WITH VARIABLE VEGETATIVE FORMS. 



plates. In the latter longitudinal divisions appear 

 usually parallel to the axis of the thread, and thus each 

 cylindrical plate becomes broken up into two or four 

 small cocci. In these crenothrix threads, therefore, the 

 individual joints divide in two or three planes. 



By continued elongation and division of the segment 

 within the sheath so much pressure is brought to bear 

 on the apex of the sheath that it opens at that point 

 and permits the escape of the rods or cocci. It some- 

 times happens that the sheath becomes gelatinous at an 

 early stage, and the cocci and rods remain in this 

 gelatinous substance. In that case they sprout and 

 burst through the gelatinous sheath, forming rods and 

 threads, and thus the original thread has numerous 

 secondary threads projecting from it like a brush. 



Very little is known as to the physiological characters 

 of the fungus ; it requires oxygen for its vegetation, and, 

 as the result of the presence of the gelatinous sheath, it 

 is very resistant to variations of temperature. 



Beggiatoa. 



These organisms occur everywhere in stagnant and 

 flowing impure waters, in sulphur springs, and in a 

 part of the bay at Kiel ; the organism forms milk- 

 white, grey, red, or violet deposits on the mud, or 

 on animal and vegetable bodies. It may be artificially 

 cultivated in infusions of animal tissues, or of algae, 

 with marsh water. The fully formed threads (the free 

 threads only represent fragments of complete threads) 

 show a distinct contrast between their base and apex, 

 in that they gradually increase in breadth towards 

 the apex, and at the lower part show a distinct trans- 

 verse segmentation. Spiral threads and fragments are 

 also formed under certain nutrient conditions ; the 

 latter pass, under certain circumstances, into a swarm- 

 ing stage. In the cells of beggiatoa sulphur is present 

 in the form of highly refracting granules with dark 

 outlines. The fungus is able to break up sulphur com- 

 pounds, more especially sulphate of soda, and to cause 



