

6o 



BOTAXICAL GAZETTE 



[JULY 



amoeboid bodies, as well as zoospores that still retained their 

 characteristic form. The cilia, however, were no longer to be seen. 

 The amoeboid bodies were watched for some hours and were seen 

 to become clustered and to move in masses; they could also be 

 seen to bud at times, much as in the case of the ciliated cell shown 

 in fig. 38. Budding of the amoebae in the infection stage has 

 been reported to occur in Plasmodiophora (11). Seedlings left 

 under these conditions developed small galls at the bases of the 

 secondary roots. 



To secure stained preparations of the Plasmodium in its early 

 stages, young alfalfa seedlings were grown in. a pot in which a 

 badly infected mature plant was also growing. At various times 

 seedlings were removed and examined. Small galls were soon 

 found at the bases of the secondary roots of some of the seedlings. 

 As soon as the plants began to produce crown buds, galls appeared 

 upon the crown (fig. 3). These young galls were fixed, imbedded, 

 sectioned, and examined after various staining processes. The 



* 



Plasmodium of the parasite was found to be widely extended in 

 the galls. An amoeboid or plasmodial vegetative condition of the 

 parasite within the host has often been noted in member-s of 

 the Chytridiaceae; Fischer (15) and Barrett (4) have observed 

 it in species of Olpidiopsis. Cornu (7) observed it, as well as 

 the amoeboid movement of the zoospores, in various members of 

 the family. He also noted a suggestion of cleavage in what he 

 called the Plasmodium of Rozella, and suggested its formation by 

 the union of many amoeboid zoospores. Fischer went so far as 

 to classify several genera upon the basis of differences in the Plas- 

 modia. He observed that the protoplasm of the parasite mingled 

 intimately with that of the host and gradually displaced it. Fisch's 

 (14) description of Reesia amoeboides is a striking suggestion of 

 the near relationship of the group to the Myxomycetes. A second- 

 ary infection of cells occupied by the Plasmodium is of common 

 occurrence. As a result, the cells of the galls are often occupied, 



not only by the plasmodium, but also by the earlier stages of 

 the parasite (figs. 39, 41). 



The nuclei in the plasmodium are very numerous, corresponding 

 quite closely in size and appearance to those in the resting spores 





























