516 PETCH : 



From Massee's figures of spores (6) one would judge that 

 he had seen ma,croconidia only ; but from the figures of 

 conidiophores, it would be supposed that he had seen only 

 microconidiophores. The figures of the latter, however, bear 

 very Httle resemblance to the elegantly tapering tube of the 

 reality ; and I have never been able to observe a flaring mouth 

 as there depicted. Went, who also obtained material from 

 the West Indies, states that the Thielaviopsis on sugar cane 

 there is identical with that found in Java ; so the suppo- 

 sition that Massee worked with a different species is 

 improbable. 



Throughout his article Massee regards the microconidia as 

 aerial, and the macroconidia as formed only within the tissues 

 of the host, or, in the case of liquid media, beneath the surface 

 of the liquid. Hence he writes with regard to the micro- 

 conidia : " This form of reproduction is a modification of the 

 one last described (i.e., the macroconidium), developing from 

 the same hyphse, and owing its structural peculiarities to 

 exposure to light and air during growth ; thus illustrating 

 from an unexpected quarter a general rule amongst groups 

 of fungi showing a transition from a subterranean to an aerial 



condition In the present instance, the advance made 



in the general structure of the microconidia over the macro- 

 conidia tends in the direction of favouring the dispersion of 

 the conidia by wind ; the entire fructification is developed in 

 the air, the conidiophores are elongated, and the conidia are 

 comparatively minute." It will be shown later that this 

 explanation is based upon incomplete observations. 



The supposed genetic connection between the Mdanconium, 

 Thielaviopsis paradoxa, and TricJiosphceria sacchari was 

 considered to be established by the following experiments : — 

 In one flask, out of three in wliich Melanconium conidia were 

 sown, microconidia of Thielaviopsis developed after twelve 

 days. Nothing of the kind developed in hanging drops, in 

 which the whole course of development could be watched, 

 and the Melanconium conidia were evidently obtained from 

 an impure source, i.e., from ordinary diseased sugar cane ; 

 under such circumstances, the evidence of a single culture 

 from uncontrolled spores is scarcely sufficient. A second 



