292 INTRODUCTION TO THE STUDY OF FUNGI 



appalling rate of development, and a great number die both for 

 want of food and because of the presence of other conditions 

 unfavourable to their existence. Vegetative multiplication 

 only takes place when the conditions are extremely favourable 

 to the growth of the organism. If nutrition is interfered 

 with in any way, or if the removal of excretionary products is 

 obstructed, or if there be a large amount of oxygen present, 

 marked changes may at once be observed in the appearance of 

 the protoplasm of the micro-organism. It becomes granular, 

 then a small bright point appears in each cell ; this point 

 gradually increases in size until its diameter may be greater 

 than that of the original organism. This large, clear, rounded, 

 ovoid, or rod-shaped node is known as a spore, or resting spore, 

 by which the species may be continued although the parent 

 should perish. The shape varies slightly in different species, 

 but in every case it has a dark limiting outline ; it is devoid 

 of colour, and is highly refractile. The dark outline of the 

 spore is usually surrounded by a pale, soft, gelatinous envelope, 

 the substance of which may, in some cases, be accumulated in 

 rather larger quantity near the two poles of the refractile body. 

 As soon as these bodies make their appearance, degeneration 

 of the protoplasm of the bacteria in which they are found 

 immediately follows, but the period at which the death of the 

 protoplasm actually takes place varies in different cases. 

 Where the spores are small they may lie for some time im- 

 bedded in the protoplasm of the cell, which, as it degenerates, 

 leaves the resting spore free to be carried about from place to 

 place, by currents of air or water, to be developed when the 

 conditions of moisture, temperature, and food supply again 

 become sufficiently favourable. Where the diameter of the 

 spore exceeds that of the bacterium, it may be situated in the 

 centre, giving rise to a spindle-shaped organism ; or it may be 

 at one end, when the organism becomes clubbed or pendulum- 

 shaped. The spore in this case appears to escape more readily. 

 This method is that which De Bary has called endospore 

 formation." 1 



Another kind of spore is called arthrospore, which is also 



1 Bacteria and their Products, by G. S. Woodhead, M.D., London (1891), 

 p. 33. 



