110 



iophores are pale straw-color to smoky brown from tip to, or nearly to, 

 the base, the color being due to the outer wall which is very brittle. Upon 

 the production of the first conidium, which is strictly terminal, the conid- 

 iophore grows onward, with a slight bend where the first conidium was 

 produced, and proceeds to bear another one. This may contTnue until 

 many conidia have been borne by the same conidiophore. If the conidia 

 are undisturbed, the cluster may have a botryose effect, but if disturbed, 

 only the youngest conidia remain, and scars and geniculations mark the 

 places of origin of the fallen conidia (Fig. 8) . The number of conidia borne 

 per conidiophore in count of 24 was as follows: 



Frequency, 15, 5, 4 

 Conidia, 1, 2, 3 



Much higher numbers than this occasionally occurred under standard con- 

 ditions (see appendix, page 180) ; and much higher numbers were the rule 

 on corn-meal agar. 



The number of septa below the first scar varied from one to four, 

 while the length in seven measurements from base to first scar was 78 

 88 /it. The length above the first scar is entirely dependent upon the num- 

 ber of conidia borne on a given conidiophore; in some cases it is equal to 

 or even greater than the length below the first scar. 



Conidia develop very rapidly upon the conidiophores. One of the 

 latter kept constantly under observation was first observed at 11 o'clock 

 to have a diameter of 6.8 /A; at 11 :15, 13.6 p; at 11 :30, 20.4 ju; at 12, 37.4 /*; 

 and at 12:30, 44.2 M . 



The conidiophores of certain other numbers, for example H. Nos. 2, 

 21, and 29, are of such very different character that the conidiophores alone 

 serve to distinguish them markedly from H. No. 1. The conidiophores of 

 H. Nos. 3, 5, 15, 16, and others, however, are closely like those of H. No. 1; 

 indeed no real distinction could be found between them. Attempts were 

 made to distinguish between these strains or species by plotting conidio- 

 phore length, septation, length of cells, etc., but nothing came of such at- 

 tempts. The length of the conidiophore is markedly influenced by air- 

 humidity (page 95), and it is probable that the rudimentary conidiophores 

 may be changed into aerial mycelium by a lowering of the air-humidity. 



CONIDIA 



The conidia and their attachment to the conidiophores are shown in 

 Plate XVII. From the basal end of the conidium to the conidiophore 

 there is an exceedingly short (2X4 /z) black stipe. As the conidium falls 



