THE MYCOPLASM HYPOTHESIS 333 



ate trichogynes and regarded the spermatia as functionally 

 vestigial. 



Christman (1905) employed Gynniocoma interstitialis, Uro- 

 myces caladii, and PJoragimdmm speciosiim to study their nuclear 

 activities. He interpreted the basal cells in aecia that gave rise 

 to binucleated aeciospores as isogametes and the aeciospore 

 mother cells as non-resting zygotes. 



In the meantime Blackman and Fraser (1906) continued their 

 studies, using Uromyces poae, U. ficariae, Fucciiiia poarwn, P. 

 malvaceanim, P. adoxae, and Melampsora rostrnpii, and concluded 

 that Blackman's earher interpretation was correct for certain rusts 

 but that Christman's was for others. A second paper by Christ- 

 man (1907), using Phragviidiinn potentillae-canadensis, found the 

 author upholding the conclusions of his earlier report. In 1908 

 Olive (1908), from studies with Triphraginmm iihnariae and Puc- 

 cinia deformans, sought to harmonize the conflicting interpreta- 

 tions of Blackman and Christman. In this paper Olive indicated 

 that, if one of the pair of cells was tardily pushed up\\ard be- 

 tween larger cells, the fusion would appear to arise from a vege- 

 tative cell, thus agreeing ^\■ith the interpretation of Blackman. If, 

 on the other hand, the cells arose side by side, there was fusion of 

 equal gametes, as stated by Christman. Results of studies of like 

 nature on approximately 40 other species by nearly a score of 

 workers are tabulated by Arthur et al. (1929, pp. 120-121). 



The My ooplasm Hypothesis 



Many investigations have centered about attempts to learn how 

 the cereal rusts hibernate. Perhaps none has directly or indi- 

 rectly stimulated more study of rust hibernation than the myco- 

 plasm hypothesis announced by Eriksson in 1894. He main- 

 tained that during the winter there is an intimate mixture of the 

 protoplasm of the rust with that of the host, so that the two 

 cannot be distinguished. In the spring, when conditions favorable 

 for growth return, the fungus plasma becomes organized into 

 definite elongated, curved bodies (Korperchen), which grow out 

 into the intercellular spaces and become mycelial. Ward (1902, 

 1903) early pointed out that the Korperchen were in reality haus- 

 toria, and violent discussion ensued. Other papers by Eriksson 

 (1897, 1903, 1922), which indicate maintenance of his firm be- 



