452 



EFFECT OF HEAT 



[Cn. XVIII 



Data from the higher fungi have been afforded by the 

 studies of WIESNER ('73) upon Penicillium. I give all of 

 WIESNER'S data, although not all are strictly concerned with 

 growth. These data show the relation between temperature, 

 on the one hand, and the interval, in days, between sowing 

 and (1) germination, (2) formation of visible mycelium, and 

 (3) spore formation, on the other : 



TABLE XLIX 



TIME, IN DAYS, REQUIRED FOR SPORES OF PENICILLIUM TO GERMINATE, PRODUCE 

 VISIBLE MYCELIUM, AND TO FORM SPORES, AT VARIOUS TEMPERATURES 



The law of growth of bacteria at various temperatures is 

 illustrated in the observations of WARD ('95, p. 458). His 

 results are epitomized in the curves of Fig. 129. 



The curve (Fig. 130) of the phanerogams Zea mais and Pisum 

 sativum, which Is constructed somewhat differently from that of 



FIG. 129. Curve of relation between rate of growth of Bacillus ramosus and the 

 temperature. The growth is measured by the period, expressed in minutes (M), 

 required for the bacillus to double its length. The relative duration of these 

 periods is expressed by the ordinates. The abscissae are temperatures. (From 

 WARD, '95.) 



FIG. 130. Curves of absolute growth in 48 hours of Zea mais and Pisum sativum at 

 different temperatures. (Data from Table XLVII.) 



