MILDEW AND BRAND. 55 



As the same Puccinia is also to be found on 

 numerous grasses^ no prudent farmer will permit 

 these to luxuriate around the borders of his fields^ 

 lest they should serve to introduce or increase the 

 pest he so much dreads. 



The germination of the spores of the corn mil- 

 dew is a very interesting and instructive process_, 

 which may be observed with a very little trouble. 

 If the spores be scraped from the sori of the pre- 

 ceding year (we are not sure that those of the 

 cun^ent year will succeed)^ and kept for a short time 

 in a damp atmosphere under a glass receiver^ 

 minute colourless threads will be seen to issue both 

 from the upper and lower divisions of the spores. 

 These will attain a length several times that of the 

 spores from whence they spring. The extremities 

 of these threads ultimately thicken^ and two or 

 three septse are formed across each^ dividing it 

 into cells_, in which a little orange-coloured endo- 

 chrome accumulates. From the walls of each of 

 these cells^ or joints^ a small pedicel^ or spicule^ is 

 produced outwards^ the tip of which gradually 

 swells until a spherical head is formed^ into which 

 the orange-coloured fluid passes from, the extremi- 

 ties of the threads.* A quantity of such threads^ 

 bearing at their summits from one to four of these 

 orange-colouredj spherical^ secondary fruits^ supply 



* Similar in all essential particulars to the germination of 

 Aregma (plate III. %. 45). 



