32 



decayed and the cause of decay not determinable. The two check 

 plants never developed any above-ground symptoms, and on June 17 

 the bulbs were entirely sound. 



SERIES 18 (plunge EXPERIMENT). 



The eighteenth series of inoculations was made March 10, to deter- 

 mine whether infections could be obtained through the stomata. For 

 this purpose I selected six pots of healthy hyacinths of the following 

 varieties: Czar Peter, Gertrude, and Gigantea. All were in full 

 bloom. 



The material for infection consisted of 1,000 cc, of distilled water, 

 sterilized in the ordinary way after adding 10 cc. of alkaline beef 

 broth. When sterile, a well-developed beef-broth culture of the hya- 

 cinth germ was poured into this flask, the fluid in which was feebly 

 clouded next morning and swarming with motile rods. On plating 

 out, it proved to be a pure culture of the hyacinth germ. Sterile 

 tumblers were filled with this fluid and the apical part of the leaves 

 of selected plants were plunged into it as follows, and left twenty- 

 three hours shaded from the light. On removal, the fluid adhering 

 to the leaves was carefully dried in situ liy exposure to the sun before 

 the plants were left, great care being taken not to infect other parts 

 of the same plants or of the checks. 



Notes on plant No. SI.— One plant of Czar Peter, six leaves plunged 4 to 7 cm.; 

 three healthy plants in same pot held for comparison. 



March ')0. No results. 



March 30. Plunged part of three leaves is paler green, and one of them has a 

 long, narrow, brown stripe. This is IS cm. by I mm., and begins 0.5 cm. below 



the tip. 



June 21. Leaves dead, bulb sound, at least to unaided vision. All of the check 

 bulbs are free from the yellow disease and all are sound, except the outer part of 

 one plateau, which has soft-rotted. 



Notes on plant No. 83:— One plant of Czar Peter, four leaves plunged 4 to 8 cm. ; 

 three healthy plants in the same pot held for comparison. 



March 80. No visible symptoms. 



July 1. Bulb entirely soft-rotted. One of the check plants has also entirely 

 soft-rotted. The other two are sound. 



Notes on plant No. ,v./.— One plant of Gertrude, eight leaves plunged 3 to 6 cm.; 

 seven healthy plants in the same pot held for comparison. 



March 30. For the last ten days one leaf has been curved downward in the 

 plunged part, and this part now bears alternating narrow green and yellow stripes, 

 the latter lying in the parenchyma between the bundles. One other leaf shows 

 slight geotropism in the plunged part and slight yellowing in stripes between the 

 bundles. The others are normal. 



July 1. The leaves are gone. The bulb has lost its center by soft rot. The 

 scales which remain show no trace of yellow bundles. The checks were also 

 examined. Two bulbs are sound. One is white-rotted and soft on one side, but 

 shows no trace of the yellow germs. The other four are entirely soft-rotted and 



gone. 



Notes on plant No. 84.— One plant of Gertrude, eight leaves plunged 3 to 5 cm.; 

 six healthy plants in the same pot held for comparison. 



March 30. No result. 



