Lehman : Conidial Formation in Sphaeronema 



159 



have been formed acrogenously within the closed cell. The wall 

 of the conidium is nearly, if not fully, as thick as that of the 

 sheath surrounding it. This sheath does not appear thinner than 

 the wall of the apical portion of the conidiophore before conidia 

 had formed within it, nor yet less thick than the wall of the 

 basal portion of the conidiophore. 



After the formation of the second conidium within the conidio- 

 phore, or sometimes after the formation of the first, the apex of 

 the sheath is dissolved and the conidia within are pushed out by 

 growth of the protoplast behind them (Figs. 3, 5, 10). The fact 

 that the opening at the end of the sheath is always bounded by a 

 smooth line indicates that the tip has been dissolved; for if it 

 were forcibly ruptured, the end should appear torn and broken. 

 As soon as the protoplast has sufficiently elongated (Fig. 4), the 

 next conidium is delimited and pushed out by continued growth 

 of the protoplast. This process is repeated a great many times 

 in succession, so that the acrogenously formed conidia appear in 

 long chains (Fig. 1). Chains of as many as fifty-nine conidia 

 have been observed. These conidia are hyaline, elongated, and 

 have rounded, or often very angular ends (Figs. 1, 3 and 5). 

 They may have a uniformly hyaline content with a single vacuole 

 at each end, or the ends may be filled with granular protoplasm, 

 leaving a clear zone at the middle. When the protoplasm at the 

 ends is granular, numerous oil droplets can be seen within it. 

 These conidia sometimes burst upon being put into water, where- 

 upon the granules exhibit a Brownian movement. This has often 

 been noted within unbroken conidia. The diameter of conidia 

 produced by the same conidiophore is very uniform, but con- 

 siderable variation in length obtains. The first conidia produced 

 are longest, the last are shortest and the intermediate ones inter- 

 grade between the two extremes. 



The method of spore formation by which the olive conidia 

 arise, differs in certain particulars from that of the hyaline 

 conidia. The conidiophore is typically short and unicellular as 

 shown in Figs. 13, 14, and 16. There are those, however, whose 

 length is equal to that of the primary sporophores (Fig. 17) and 

 they may resemble these in shape. When the conidiophore 



