144 



PHYCOMYCETEAE 



Fig. 48. Protomycetales, Family Protomycetaceae. (A-F) Protomyces macro- 

 sporus Unger. (A) Young mycelium with intercalary young resting sporangia. (B) 

 Germination of resting sporangium. (C) Protoplasm forming parietal layer of spore 

 mother cells. (D) Spore mother cell divided into spores. (E) Discharge of ball of 

 spores. (F) Successive stages in fusion of spores, showing union of nuclei in the conju- 

 gation tube and division of the zygote nucleus. (G) Protomycopsis leucanthemi Magn., 

 terminally formed resting sporangium. (A-E, G, after von Biiren: Beitr. Kryptogamen- 

 flora Schweiz, 5(l):l-95. F, ibid., 5(3):l-94.) 



others scattered at various depths. In germination the sporangia of 

 Taphridhim produce their spores without breaking the exospore, while 

 those of the other genera burst the exospore on one side and the contents 

 bulge out like a balloon, still surrounded by the inner wall. The nuclei in 

 Protomyces all migrate to the periphery and a large central vacuole is 

 formed. The thin layer of peripheral cytoplasm is divided by cleavage 

 planes, starting at the outside, into little uninucleate cells which divide 

 twice (meiosis?) forming four ellipsoidal spores out of each cell. These 

 spores then mass at the center or apex of the sporangium and by breaking 

 of the latter are thrown out along with the slimy contents of the vacuole. 

 In some species, apparently not in others, the spores fuse by twos after 

 being set free, sometimes before. The nuclei unite in the conjugation 

 tube. The spores in culture media germinate to form yeast-like cells but 

 when inoculated on the proper host produce endophytic mycelium. (Fig. 

 48.) 



The affinities of this family are exceedingly uncertain. The final divi- 



