Damping Off. 329 



velopment of another form than the purely vegetative portion of the 

 plant, and either simple resting spores are developed, or if sexual 

 organs are present, then oospores. The number of resting spores 

 varies from one to ten or even twenty in large prothallial cells 

 where the botryoid fungus is well developed. The resting spores 

 occupy the central portion of the mass and are surrounded by the 

 smaller and terminal cells of the plant which now are empty. The 

 resting spores are rounded, sometimes oval in form, and when 

 mature are bounded by a very thick wall consisting of three coats, 

 which are smooth, but sometimes appear roughened by the closely 

 cohering cell walls of the collapsed surrounding terminal portions 

 of the botryose mycelium. The portions which become resting 

 cells are always the larger and centi'al portions. They are much 

 larger at the time of the formation of the resting spores than when 

 the fungus is in the vegetative stage, and since at first there appear 

 to be no cell walls intervening it would seem that their increase in 

 size came chiefly from the outer and smaller cells giving up to them 

 their protoplasmic contents rather than that the additional nutriment 

 came from the cell of the host which by this time is nearly ex- 

 hausted. However, this point was not determined. The wall of 

 the young resting spore is at first, very thin and the protoplasm 

 finely granular. The mature resting spore presents a very coarsely 

 granular protoplasm the granules rounded in form and closely 

 packed together. 



Propagation also takes place by the production of non-motile 

 Conidia from monosporous s])orangia. 



The conidia are oval or broadly obovate, colorless cells, with a 

 thin wall and measure from 15/y to 25^ in diameter. In germi- 

 nating, unless they are lying entirely immersed in water or in an 



Explanation of Plate IV. Completoria complens Lohde. 



Fig. 42, botryose cluster of plant body after being placed in water, the per 

 ipheral cells germinating and forming long tubes. 



Fig. 43, plant body, some of the central cells forming resting spores, and some 

 of the peripheral ones developing conidia. 



Fig. 44, plant body in one cell of the host, the peripheral cells developing 

 tubes which penetrate adjacent cells of the prothallium. 



Fig. 45, two young plants in one cell of the host having entered from an 

 adjacent cell, early stages in the branching and development of the botryose 

 plant body are shown. 



All figures drawn with aid of the camera lueida and magnified 30 times more 

 than the scale. Scale, 1 millimeter. 



