(icini'nmi'iO]i of Spores. 21 



not the most suitable medium for obtaining the best results. In many cases 

 the couidia were formed, but they were often so passive that they did not germi- 

 nate, and without some additional means of quickening their germination and 

 development it was diflicult to account for the wide distribution of the snuits. 

 I have found a sterilized infusion of hay a good culture medium, and have also 

 used a variety of substances, such as malt extract, soil extract, somatose, 

 Cohn's modified solution, &c. 



In onio cases it is v; ry difficult to get a spore to germinate even when the 

 various nutrient media are tried in addition to water. It may be that it is 

 not the proper season of the year, and some spores may require a rest before 

 starting germination. I may take Ustilago calandrinice, CHnt., as an illus- 

 tration of this class of spore. The spore i of the Tilletia type, with regular 

 reticulations of the epispore, and it was desirable to germinate it in order to 

 settle the genus. The only material in my possession at first was fully ten 

 years old, and it failed to germinate ; but that might be owing to its age. 

 Fortunately I came across fresh material in October, 1908, and it was also 

 supplied to me in November, as well as in January, 1009. The fresh spores 

 were placed in both tap and distilled water, as well as in a decoction of the 

 plant itself, also in ammonium nitrate, lactic acid, tannic acid, an infusion 

 of sugar-beet, sugar solution, and Cohn's modified solution. At the end of 

 six days only a very few germinated in distilled water and formed conidia, as 

 in Ustilago. But in the other solutions, although some of them were kept 

 till the fourteenth day, there were no signs of vitality. 



In proper culture media the spore germinates as usual, and produces a 

 germinal tube, but instead of remaining short and forming conidia, it often 

 continues to develop and gives rise to sprouting conidia, which multiply by 

 budding after the manner of yeast. Or the germinal tube may grow 

 luxuriantly and produce a much-branched mycelium, from which in the 

 fluid itself or in the air conidia are formed. These conidia sprout at the end 

 again into one or several conidia. and we may distinguish them as water or 

 air conidia, according to the medium in which they are produced. 



There is thus a great variety of reproductive bodies, although there is 

 only one kind of spore, and it is quite likely that the conidia, sprouting conidia, 

 and aerial conidia of the smuts are just as efficient means of distribution as the 

 different kinds of spores among the Eusts. 



A w ord of caution is necessary, however, as to the interpretation of results 

 ol)tained from " pure cultures," as they do not necessarily represent Avhat 

 actually takes place under natural conditions. The researches of Klebs,' 

 Kaufmann,' and others have shown that the formation of reproductive 

 organs of a particular kind or their suppression is largely determined by food 

 and environment. Klebs was able to control at will the reproductive 

 processes in certain fungi, according to the composition and concentration 

 of the nutrient medium, as well as by the temperature, presence or absence 

 of light, &c. There is no reason to doubt that the same principle applies to 

 smuts, and that it will tend to explain the discrepancies in the results 

 obtained by different observers in the germination of the spores under 

 different conditions and in different media. 



As has already been shown, the germination of the spore is uot always 

 easy of accomplishment, for we do not always know the precautions to be 

 taken. Some spores are capable of germination immediately after being 

 gathered, others require a period of rest. Some germinate in the water or 



