294 NINETEENTH REPORT. 



conidiophores, or even a primary brancli becomes modified into a 

 conidiopliore and bears a spore. Tliis is the source of some of the 

 abnormally long conidiophores. The process of spore formation is de- 

 lineated on Plate XIII, Figs. 21-29. 



The general method of spore formation is analogous to the process 

 among many of the AlternariaS;, where a spore sends out a little swelling 

 from the beak end, wliich later enlarges, becomes muriform, and develops 

 into a spore like that Avhich gives rise to it. 



Tlie method of sjiore formation as observed by the author does not 

 agree with that described by Cavara (1890) or Malkoff (1902), who 

 state that the apical cell of the conidiophore swells, and itself becomes 

 differentiated into the spore. The author has never witnessed this pro- 

 cedure. 



In a 5% dextrose solution, growth proceeds to the formation of spores, 

 but the germination process develops abnormal swellings. In a few 

 instances, a cell budding from the spore was seen to enlarge to a size 

 equal to that of the spore which gave rise to it, and become divided by 

 one or two lateral cross walls, giving it the appearance of a young spore 

 (PI. XIV, Fig. 7). Though this was not seen to develop into a mature 

 spore, it might possibly have done so under proper conditions. This may 

 be evidence of a tendency towards an Alternaria-like habit. Some species 

 of Macrosporium are known to develop the Alternaria liabit in culture. 

 The cause of these abnormalties is not due entirelv to the nature of the 

 medium, since they did not appear in a series of 5% dextrose solution 

 cultures prepared at another time. The mature mycelium also germinated 

 readily. In water thin hyalin threads, similar to the germ tubes from 

 the spores, are produced. Old conidiophores from which the spores have 

 fallen often germinate from the tip cells, sending out long vacuolate tubes 

 with occasional swellings (Plate XIV, Fig. 9). 



Tlie amount of germination of spores from young cultures is prac- 

 tically 100%. In cases where old spores were used, the germination 

 percentage was found to vary from 70 to 90%. 



CULTURAL STUDIES. 



The original culture of tlie fungus was obtained from tlie dried ma- 

 terial, which at the time was 18-20 months old. Dilution plates were 

 poured, using corn meal agar. A single spore was marked, and when 

 germination occurred it was removed together with a small block of 

 agar containing it and transferred to prune-juice agar. From the colony 

 which developed transfers were made, originating the stock cultures. 



The comparative cultural study of M. sarciiiaeforme has not revealed 

 any striking morphological divergences. The fungus grows readily on 

 a large variety of media. Three groups of media were used: agars. 



