212 RESEARCHES ON FUNGI 



Entyloma menispermi, E. lobeliae, and E. linariae. In all probability 

 further investigation will show that violent discharge of the secondary 

 conidia, coupled with drop-excretion, occurs in many other Tilleti- 

 aceae, and, in general, is characteristic of the group. 



This chapter contains a detailed account of investigations on 

 the production and liberation of the so-called secondary conidia of 

 Tilletia tritici made by T. C. Vanterpool working in conjunction 

 with A. H. R. Buller in the Winnipeg laboratory. 



Bunted Ears and Grains of Wheat. — In an infected wheat plant 

 the mycelium of Tilletia tritici, on entering an ear, usually invades 

 all the spikelets and ultimately produces chlamydospores in every 

 grain, so that all the grains become converted into smut-balls 

 (Fig. 100). However, it sometimes happens that the mycelium, on 

 entering an ear, infects some grains and not others. Thus in the 

 same ear there may be present both smutted and sound grains of 

 wheat. The grains of two such partially bunted ears of Common 

 Wheat were removed and set out in their proper order and then 

 photographed. The photograph is reproduced in Fig. 101. The 

 first and second rows of grains shown were taken from the two 

 rows of spikelets on one ear, while the third and fourth rows of 

 grains were taken from the two rows of spikelets on the other ear. 

 The darker grains were all bunted, while the lighter grains were 

 perfectly sound and free from the parasite. Dr. W. F. Hanna has 

 informed me that several times in bunted ears of wheat he has 

 observed individual grains which were in part sound and in part 

 bunted. 



Figs. 102 and 103 show healthy and bunted grains of Common 

 Wheat (Marquis) respectively. Fig. 104 shows some smutted grains 

 of Durum Wheat : the two grains to the left are seen in surface 

 view, while the other grains to the right are seen in section. Each 

 smut-ball consists of a very thin light envelope derived from the 

 pericarp and testa of the grain and of a black core consisting of a 

 dense mass of dark-brown chlamydospores. As a result of ten trials 

 with a counting apparatus (a haemocytometer), the number of spores 

 contained within a single large smut-ball on wheat was estimated 

 to be 12,125,000.! 



1 These Researches, Vol. 1, 1909, p. 95. 



