212 GERMINATION OF SPORES 



spora lini, and many other fungi, the spores may germinate by 

 buddine and may continue to grow by budding. In a goodly 

 number of species the spores first form a tube, and subsequent 

 growth is wholly or in large part by budding. 



Some spores require both water and a supply of nutrient sub- 

 stances before they can be made to germinate. A lining of proto- 

 plasm remains in their spore cavity, and the spore becomes an 

 integral part of the mycelium. 



Spores seldom form more than a single germ tube or at most 

 a few. Exceptions are the multicellular spores or large spores. 

 Each cell of a multicellular spore normally behaves as an entity. 

 Lar«e spores, such as those of Pertusaria and Megalospora, may 

 develop simultaneously fifty or more germ tubes. The tubes in 

 these genera are emitted through pores in the thick wall, but they 

 possess no other peculiarities. 



METHODS OF TESTING SPORE GERMINATION 



Hoffman (1860) initiated the hanging-drop technique, which 

 now employs Van Tieghem cells and which is now widely used 

 in spore-germination tests. It is employed successfully not only 

 with liquid but also with semisolid media. This method has cer- 

 tain obvious advantages over the use of drops of water containing 

 spores and placed on microscopic slides and over the implanting 

 of spores on media in Petri dishes. None of these features seems 

 to be so important as an understanding of how to secure repro- 

 ducible results of germination trials. It is quite apparent that 

 there is little accord among the results of investigations on spore 

 germination. As McCallan and Wilcoxon (1932) have shown, 

 the variations in spore germination that have been reported may 

 be attributed to two causes: faulty technique and variation in 

 sampling. Among the common errors which McCallan and Wil- 

 coxon enumerate are: (j) failure to state the number of spores 

 counted, either germinated or not germinated, making it impos- 

 sible to determine from statistical analysis the decree of siimiri- 

 cance to attach to the results; (b) counting the control germina- 

 tion as 100 c ; and adjusting the treatments accordingly, thus pre- 

 venting adequate comparison, because small differences between 

 controls will result in large differences between treatments; (c) 



