REPORT OP COMMITTEE ox PUBLICATION 131 



branches which are in turn branched several times. Each branch is termi- 

 nated by two to four, short sterigmata whose ends, after the dispersal of the 

 conidia, are concaved. The sterigmata are about 5 to 12/t long and 2 to 3,u 

 in diameter. 



The walls of the conidiophores are thicker than those of the mycelium 

 and are composed at least partially of cellulose, staining a bluish purple with 

 zinc chloriodide. At irregular intervals in the primary axis, branches o'r the 

 sterigmata, there occur septa which are very much thicker than the walls. 

 These are claimed by Mangin (1890) not to be true cross-walls but merely 

 plugs of callose. When stained with zinc chloriodide they are not tinted 

 but, as in the case of the mycelium, do so after the conidiophore has been 

 boiled in potassium hydroxide. 



To determine whether the conidiophores are composed of p.u.re cellulose 

 they were treated with a cellulose solvent, cuprammonia (Schweizer's 

 reagent). A preliminary observation was made of the action of this -^plvent 

 upon cotton fibers (pure cellulose). The first evidence of its. action is a 

 swelling of the fibers to at least double their original diameter, followed 

 shortly by their rapid disappearance. The walls of the conidiophores*, when 

 treated in the. same manner, also swelled to about twice their normal thick- 

 ness but they do not then rapidly dissolve (PL III, fig. 1). The basal portion 

 exhibits a peculiar reaction, seeming to burst outward and to disintegrate 

 except for a thin inner sheath (PI. Ill, figs. 1 and 3). Sometimes the large 

 proportion of the conidiophore assumes this aspect, but in practically every 

 case the distal end remains apparently intact. A logical interpretation of 

 these reactions is that the conidiophores are composed of cellulose or a 

 cellulose-like substance but are lined with another material, possibly callose. 



Before the formation of the conidia, the conidiophore is filled with 

 protoplasm which is abundantly provided with nuclei. The conidia are 

 formed by the swelling of the end of the sterigmata into which a portion 

 of the protoplasm passes. After the mature size is attained a septum is 

 laid down separating the conidium from the sterigma. According to Istvanffi 

 (1913) a single nucleus passes into each spore at this time and its division 

 produces the multinucleate condition obtaining in the mature conidium. He 

 also states that the cross-wall is laid down when the conidium is from one- 

 half to two-thirds its mature size. 



The mature conidia are extremely variable in size and shape. Some are 

 almost globose, others are long and narrow, but the majority are ovoid. 

 They are attached to the sterigmata at their smallest end. Disarticulation 

 occurs very easily, being produced by the breaking or solution of a small 

 lenticular area which separates the conidium from the sterigma (PI. Ill, fig. 

 5). The ease with which this substance is broken is shown by the fact that 

 only a slight jarring is necessary to release the spore. It is also very 

 readily soluble in water hence the exceeding difficulty of obtaining a mount 

 in water of the attached spores for microscopic examination. One may 

 observe many conidia still fastened to their sterigmata when in the dry 

 state but if a drip of water is placed upon the mass in a moment all of the 

 conidia will be freed. 



Cornu (1882) mentions this substance and states that it is due to its 

 extreme solubility that the conidia are freed during moist weather. He 

 figures it, however, as a wall which is so tightly compressed between the 



