66 LON A. HAWKINS 



flanges at the ends, the flanges extending upward about 1.3 cm. and down- 

 ward about 0.4 cm. They were so bent that the lower flanges of one 

 tray fitted outside the upper flanges of the next lower one, and many 

 trays could thus be arranged in a compact and rigid pile without any 

 disturbance to the slides. The bottom of each tray was perforated with 

 circular openings about 1.5 cm. in diameter and 0.5 cm. apart, to facilitate 

 circulation of air. Each tray carried fourteen slides. The slides were 

 always transferred to and from the thermostat by means of the trays, a 

 whole series of cultures being thus moved together. 



The cultures were kept during germination in an electrically heated and 

 automatically regulated thermostat, in which the temperature was main- 

 tained at or near 25 C. As the temperature of the room in which the 

 thermostat was placed sometimes rose above 25, it was necessary to 

 install apparatus for absorbing heat at such times. To accomplish this, 

 several coils of thin-walled copper tubing carrying a continuous stream of 

 tap water were placed at the top of the thermostat, surrounding a small 

 motor-driven fan, the latter insuring air circulation. The air of the 

 chamber then tended to assume a temperature several degrees below that 

 of the laboratory, and the thermostat acted as though standing in a 

 cold room. 



EXPERIMENTATION, 



In these studies, any renewed activity in the protoplasm of the spore 

 was considered as germination. Several forms of such renewed activity 

 are exhibited by the conidia here employed. Without any alteration in 

 size or shape, a portion of the spore may become nearly or quite opaque, 

 thus appearing dark brown or black by transmitted light. A papilla may 

 be formed at any point on the surface. Such papillae may or may not 

 enlarge to form rounded bodies, and may either remain hyaline or become 

 apparently darkened. Papillae may enlarge to form irregularly shaped 

 bodies or <may extend outward as markedly thickened tubes. Lastly, the 

 growing papillae may take the form of slender tubes. The latter type of 

 germination always occurs in distilled water and the tubes attain, in a 

 period of eighteen hours, a length at least twice as great as that of the 

 spore itself. In the following treatment germination will be considered 

 " normal " wherever tubes of the last mentioned type, at least twice the 

 length of the spore, were produced in eighteen hours. 



In the present section will be considered the various effects upon germ- 

 ination brought about in the presence of the following salts either alone 

 or in certain combinations : 



Ca(NO 3 ) 2 Pb(NO 3 ) 2 Ni(NO,,) 2 



Mg(NO 3 ) 2 Zn(NO 3 ) 2 Cu(NO 3 ) 2 



KNO 3 A1(NO 3 ) 3 CuSO 4 ' 



