10 



which have been made in the technique of bacteriology than a perusal 

 of the best earh' papers. 



It is not unlikely that the additions which I shall make will also be 

 insufficient, exclusive of the pathogenic test, to differentiate this 

 germ ten or twenty years hence, but they will at least help toward 

 definitely settling the group to which it belongs. Readers who wish 

 merely a summary of Dr. Wakker's conclusions will find it in my 

 critical review already cited, and those who wish to read the original 

 papers will find the necessary references in the same paper. ^ Inas- 

 much as that review is very full and readily accessible, I may be 

 excused from going over the ground again in this place. 



SOURCE OF MATERIAL. 



The hyacinth bulbs from which the germ that I have studied was 

 isolated were said to be in the first stages of the yellow disease, and 

 were sent to me in October, 1896, by Messrs. Van Meerbeck & Co., 

 growers of bulbs at Hillegom, near Haarlem, Netherlands. The bulbs 

 were sound externally. They had been " visited," ^ and some of the 

 vascular bundles of the inner scales were yellow, broken down, gummy, 

 and full of bacteria. Penicillium was also present in places. No 

 difficulty was experienced in isolating a yellow micro-organism from 

 the broken down bundles of one of these bulbs, and subsequently the 

 same germ was isolated from another bulb of the same lot. By plant- 

 ing a third bulb the disease was also obtained tlie following year in a 

 daughter bulb. I have now cultivated this organism over four years 

 in hundreds of cultures on a great variety of media, and have 

 also obtained very satisfactory infections— infections so exactly like 

 those described by Dr. Wakker that there can be no doubt either as 

 to the nature of the organism with which I have worked or as to the 

 substantial accuracy of Dr. Wakker's conclusions respecting its patho- 

 genic properties. 



INOCULATIONS OF 1897. 

 SERIES 1 (HYACINTHS). 



The first set of inoculations was made February 16, 1897, from a 

 pure beef-broth culture. Eight vigorous hyacinths were inoculated. 

 They were all of one variety, a robust, single-flowered, deep-blue sort 

 (name unknown). The plants were just coming into blossom and 

 were the picture of health, six of the eight bulbs being large and well- 

 stocked with food, and the other two smaller daughter bulbs. Part 

 of the inoculations were by means of ordinary needle punctures and 



1 The Bacterial Diseases of Plants: A Critical Review of the Present State of 

 our Knowledge, Parts III and IV, The American Nati(ralist, October and Novem- 

 ber, 1896. pp. 797, 912. 



2 Removal of the top of the bulb with a sharp knife for purposes of inspection 

 is called •• visiting." This is done after the bulbs are dug. 



