DISEASES OF FIELD & GARDEN CROPS. [CH. 



manner in the disease pustules, the epidermis of the host 

 plant bursts in an irregular manner, and the conidia are 

 set free. Each conidium is filled with finely granulated 

 protoplasm or vital material. 



When the conidia approach maturity in damp air or 

 water, the interior substance of each may be seen divided 

 into a definite number of portions, generally from five to 

 eight ; each portion presenting a pentagonal or hexagonal 

 form bounded by a white line, precisely in the manner of 

 the conidia of the fungus of the potato disease described 



X400 



Pro. 32. WHITE RUST OF CABBAGES. 

 Cystopus candidus, Lev. Enlarged 400 and 1000 diameters. 



farther on in this work. Each of the contained portions 

 within the conidium is now really a secondary spore, and 

 the body which was at first a simple conidium has now 

 become a sporangium or spore case technically, in this 

 instance, called a zoosporangium, or case containing zoo- 

 spores or spores endowed with an animal-like motion. 

 If we take a perfectly ripe conidium, sporangium, or 



