MICHIGAN ACADEMY OF SCIENCE. 293 



PHYSIOLOGICAL RELATIONS OF THE CASUAL ORGANISM GERMINATION STUDIES. 



The various studies in the germination plienomena of the fungus were 

 made in the usual Van Tieghcin cells kept at room temperature 

 (20°-2i° C). 



The spores of M. sarcinaeforme germinate readily in either tap or 

 distilled water. If taken from a young culture^ they begin to germinate 

 within an hour. Usually within six hours every viable cell of the spore 

 lias sent out a germ tube. These tubes are at first hyalin and finally 

 granular, but become much vacuolated as they elongate. The limit of 

 growth in water is reached after 36-18 hours. At this stage, the mycelium 

 is somewhat branched, septate, and vacuolate, with a length of 500 to 700 

 microns. Spore formation in water was not observed. Malkoff (1902) 

 mentions observing the formation of new spores in a hanging drop, but 

 does not state what medium he used. 



In clover juice, the germ tubes are at first hyalin but more closely 

 granular than those growing in water. They begin to swell at the base 

 very early, and darken in color. Tliis basal swelling is soon cut off by 

 a cross wall and rounds up into a cell containing one or more large cen- 

 tral vacoules. These vacoules enlarge much faster than the cells contain- 

 ing them (PL II, Fig. 5 and 6). From this time on the growth of the 

 tubes is more rapid; the mycelium becomes coarsely granular, turning to 

 a brown color which is darkest near the spores and shades, off to hyalin 

 at the growing tip. As the mycelium becomes older, the cell walls 

 thicken, and oil globules appear. Within three days the colony attains 

 •a diameter of 2-i mm. 



Spore formation: 



The conidiophore begin to differentiate about the fourth day. A short 

 branch usually at right angles to the main thread, begins to swell at the 

 top. This branch may or may not elongate as the swelling progresses. 

 The swollen cell darkens, and is further differentiated from the vegetative 

 cells in that it is finely granular and contains no oil drops or vacuoles. 

 The first sign of the spore, which usually begins to appear on the fifth 

 day, is a small, hyalin protuberance from the swollen tip cell. This 

 enlarges rapidly, until it emerges as an oval, hyalin cell perched on the 

 tip of the conidiophore. A horizontal cross wall divides the cell in the 

 middle, and soon the first longitudinal divisions appear. As the spore 

 matures the color gradually darkens to a deep brown or fuliginous color, 

 the constriction at the middle becomes more prominent, and the remaining 

 subdivisions are produced. As a rule, the outer cell wall and the median 

 division wall become more thickened than the partition walls of the 

 sjjore. Sometimes the end of the mycelium wliich gives rise to the 



