276 



the work Avliich luis been performed is simply a continuation of some in- 

 vestigations liegnn dnriny tlie season of 1898. and reported in the Acad- 

 emy Froceedinjis for tliat year. pp. (54-70. At that time work was under- 

 taken witli both wlieat and oats smut. l)Ut on account of the fact that the 

 wheat smut spores did not remain viable under laboratory conditions 

 this portion of the Avork had to be abandoned. Further opportunity for 

 study of the wheat smut did not present itself till last summer. A con- 

 siderable quantity of smutted heads was collected from last year's wheat 

 crop just after the grain headed out. and lief ore the spores were lilown or 

 washed off the rachis. This material was kept in the laboratory until 

 needed for use. Spores mounted in hanging drop cultures over moist cells- 

 showed good germination in distilled or tap water at the time the material 

 was collected, but in the coiu'se of two or three weeks failed to germinate. 

 As these results corresponded with those of ]S!>8. it was decided to try 

 germinating them in some nutrient solution. Accordingly a. Pasteur sugar- 

 solution Avas substituted for the Avater, Avith the result that a vigorous, 

 germination Avas obtained. 



In order to in.sure a uniform lot of spores for the culture experiments^ 

 a sufficient quaytity of them AA'ere jarred from the smutted heads, and 

 after remoA'al of the detritus by screening, they were thoroughly mixed 

 and collected in a recejitacle from Avhi<-h fresh supplies Avere draAvn as 

 desirefl. 



Trciitmeiit of ihc v/Jo/r.s". — The spores AA-ere treated in muslin sacks, one 

 corner of which Avas AA'eighted AA'ith a small qiiantity of shot in order to 

 eari-j' the sacks doAAii into the solution and maintain them in pi'oper posi- 

 tion while being treated. 



In treating the spores, especially in the formalin solutions it was 

 found absolutefy essential that only a miiuite quantity of spores !»e taken, 

 otherwise they Avere apt to collect in masses, and in this way the solu- 

 tion did not readily permeate the whole mass. WhencA-er this occurred, 

 in the shorter periods of treatment, spores taken from the interior of these 

 masses aa-ouM iinariably sIioaa' germination. 



Formalin treotmevf.—The strength of formalin solutions iised were .18, 

 .25 and .5 per cent. The periods of treatment to which the spores were 

 subjected in these solutions AA^ere one-quarter, <me-half. one. and tAVO 

 hours, the four lots of spores being treated at the same time, each l>eing 

 successiA'ely remoA'ed without in any AA'ay disturbing the remaining ones. 

 The treate<l spores were mounted :is soon as possible after removal froncb 



