FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 5 



METHODS USED IN THE BASIDIOSPORE STUDIES. 



The basidiospores used in the tests were collected and kept on 

 sterilized glass slides, as a rule, although the spores of Lentinus 

 lepideus were collected upon sterilized black paper. The spore 

 prints were obtained in the usual way, care being taken to prevent 

 moisture from collecting upon the prints for it was found early in 

 the work that such condensation water affected the viability of the 

 spores. The prints were then preserved in Petri dishes in an ice 

 box in which the temperature was 12° to 16° C, and the relatiA r e 

 humidit3 T 40 to 45 per cent. For the general purposes of experi- 

 mental work the glass slides for spore prints were preferred to the 

 black paper because of ease of manipulation and cleanliness. 



All spore germination tests were made upon the surface of agar, 

 usually in Van Tieghem cells. The germination of spores upon the 

 surface of the cooled agar had certain advantages. The question 

 of the oxygen supply available for the spores was obviated. It was 

 easier to count percentages of germinated spores when they were all 

 in one plane. And besides there was no danger of subjecting the 

 spores to unfavorable temperatures, as may be the c&se when they 

 are introduced into melted agar. A temperature only slightly too 

 high, produced either by a hot needle or hot agar, materially reduces 

 the percentage of germination. For purposes such as drawing, 

 photograph}-, or examination by the higher powers of the microscope, 

 sowings of spores were made upon thin films of agar poured on 

 sterile slides kept in moist chambers under sterile conditions. The 

 agar media used for all experimentation contained 2 per cent of 

 agar with 2^ per cent of malt extract, filtered through filter paper in 

 a Biichner filter and autoclaved 30 minutes at 8 pounds pressure. 

 Occasionally, for the taking of photomicrographs, water agar (malt 

 extract omitted) similarly filtered was used because of its greater 

 transparency. Unless otherwise specified, all germination tests were 

 run in an incubator at 28° C. 



GERMINATION OF THE BASIDIOSPORES. 



The germination of the basidiospores of the species under con- 

 sideration presents no features unusual for hyaline hymenomycetous 

 Bpores. All of them swell more or less in the process. The spores 

 of Leu-site* Mp'iarhi. L. triihca. and Lehibws lepideus swell to very 

 little more than the diameter of the germ tube, so that they are not 

 very conspicuous in the thalli of the germinated spores (PI. III. 

 tig. 1 : PI. IV. fig. i : PI. V. fig. 2). Fonies roseus spores swell con- 

 siderably (PI. V, fig. 1). hut, those of Trwmetes serialis swell much 

 more (PL IV, fig. 5). These hitter spores swell to a large globular 

 body of many times the volume of the original spore before the germ 



