Dec. 23, 1918 



Parasitism of Cronartium ribicola 



621 



alcohol; and (2) Flemming's fluid, both weak and strong. The first was 

 used for pine material only; the second for both pine and Ribes spp. 

 Formalin-alcohol gave excellent result not only for gross mycelial char- 

 acters but also in some cases for nuclear phenomena. The material sec- 



10 glistenioq drops 

 ODpioe barK 



.6- 



oraDge-YeUow 

 blisters 01? 

 pir)6 borK 



On 

 The 

 prowyce 

 wbich sprout 

 frow The spores 

 ID Tbe columoe 



Id 

 ■5^^/ oraoqe-Yellow 

 \.y^^^^^ pustules or) tbe 

 under side of 

 currflpt aod qooSeberrr 

 leaves 



hflir-liKe co\vwn5 

 on tbe under side of 

 curropt and (^ooseberrv leaves 



€"-' 



Fig. I. — Diagram representing the life cycle of Cronartium ribicola. The spores are drawn to approxi- 

 mately the same scale and are numbered in the order of their appearance: i, pycniospore; 2, seciospore; 

 3, urediniospore; 4, teliospore; 5, sporidimn. The repetition of the figure 3 in the broken line between 

 the urediniospore and the teliospore indicates that the urediniospores appear in successive generations in 

 a single growing season, a, A young pine branch at the time infection usually takes place: b, pycnial 

 drops; c, pycnial spots: d, aecia; e, the dots on the currant leaf represent uredinia; /, the dots represent 

 uredinia and the dashes telial columns; g, this figure represents the condition of the infected leaf in the 

 fall when the telial columns are the predominant spore fonns. 



tioned easily, either in paraffin or celloidin, and stained well with safranin 

 and Lichtgrun or Haidenhain's iron-alum hematoxylin. Both concen- 

 trations of Flemming's fluid were very satisfactory. The material was 

 cut into pieces not over 3 mm. square, fixed for 24 to 48 hours and then 



