224 RESEARCHES ON FUNGI 



conidium, having failed to be discharged, has germinated in situ 

 instead of after discharge . Similar abnormalities have been observed 

 by me in the Rust Fungi, and for Puccinia graminis they are 

 illustrated in Volume III, Fig. 203, h-l (p. 503). 



Brefeld 1 described and illustrated the germination of secondary 

 conidia whilst still attached to H -shaped pairs of primary conidia in 

 Tille.tia tritici, T. decipiens, T. controversa, and T. zonata. He did 

 not know that, under favourable conditions, the secondary conidia 

 of Tilletia species are violently discharged from their sterigmata 

 and he was therefore unaware that the germination of these 

 secondary conidia while still attached to sterigmata is abnormal. 



(3) The conjugated pairs of primary conidia, just as in (1) and 

 (2), remain seated on the promycelium. However, when they 

 germinate they give rise not to a sterigma and secondary conidium, 

 but to a slender germ-tube (Fig. 109, B, e and g). The. germ-tube 

 grows out into the air and, sooner or later as it elongates, the 

 H -shaped pair of primary conidia becomes detached from the 

 promycelium and, bearing the germ -tube with it, falls on to 

 the substratum. If the germ -tube then comes into contact with 

 nutriment, it may develop into a branched mycelium which may 

 give rise to numerous secondary conidia. The mode of development 

 just described and illustrated in Fig. 109, B, is certainly abnormal 

 and, as the primary conidia do not produce any secondary conidia 

 whatever, it may be regarded as still more abnormal than that 

 described under (2) and illustrated in Fig. 109, A. As in (2), it occurs 

 under unfavourable conditions (closed chamber, excess of moisture). 

 (4) The pairs of conjugated primary conidia do not remain 

 seated on the promycelium but, shortly after conjugation has taken 

 place, become detached from the promycelium and settle on the 

 substratum. Here, as shown in Fig. 110, each H -shaped pair of 

 primary conidia develops a sterigma and secondary conidium, and 

 the conidium is shot away into the air by the drop-discharge 

 mechanism. As the secondary conidium is being produced, the 

 protoplasm of the pair of primary conidia passes into it en masse, 

 and after the secondary conidium has been discharged, the H -shaped 



1 O. Brefeld, Untersuchungen iiber Pilze : Heft V, 1883, pp. 149-150, Plate XII. 

 Figs. 31a and 32 ; Heft XII, 1895, pp. 161-164, Plate X, Figs. 1, 2, 4, and 6. 



