PLANTS AS CARRIERS OF DISEASE. 1 85 



was already well known, viz., that bacteria are commonly present in the air and conse- 

 quently liable to be found on the surface of everything, not excepting the surface of the 

 flowers with which the author experimented. Florists and flower lovers need give them- 

 selves no particular uneasiness, since Dr. Freire's conclusions do not necessarily follow from 

 his experiments. As to the correctness of his identification of species, the paper offers no 

 means for judging. The author's conclusions are : 



(i) That animal pathogenic bacteria. Streptococcus pyogenes, Bacillus pyocyaneus, etc., are 

 normally present in flowers which can, as he says, " noteworthily store up numerous germs, which 

 may subsequently finish their development in the better adapted tissues of animals or plants;" 

 (2) that there is some hidden relation between the colors of flowers and the bacteria found on them, 

 e.g., the color of the colonies of Leptothrix ochraceae and the very pale rose color of the Rothschild 

 rose, or the egg yellow color of Micrococcus cruciformis and the yellow of Hibiscus rosa-sinensis; (3) 

 that certain bacteria, called by him osmogenes ' ' reproduce odors analogous to those liberated by the 

 essential oils of the flowers where they live. " 



Two new species are very imperfectly described. Micrococcus cruciformis from the 

 anthers of Hibiscus and Bacillus gallicus from Rosa gallica (centifolia). From Ipomoea 

 quamoclit 1,. he isolated an organism having the characters oi Micrococcus salivarius pyogenes 

 and another identified as Spirillum plicatale. From the flower of the peach he also ob- 

 tained something identified as Bacillus pyocyaneus. 



Uffelmann's experiments (1892) showed that the cholera vibrio might be disseminated 

 on the surface of fruits and vegetables. 



He moistened the surface of a ripe apple with some drops of liquid from a cholera stool which 

 dried within 15 minutes. Then after 5, 10, and 20 hours he transferred small particles of this con- 

 taminated skin direct to gelatin roll cultures and to tubes of bouillon for 24 hours at 35° C, after 

 which gelatin rolls were made. In each case numerous colonies were obtained. After 24 hours, 

 however, only a few colonies were demonstrable, and after 30 hours, very few. After 48 hours no 

 colonies were obtained. From the surface of an apple treated in the same way except that it was 

 kept under a bell jar, cholera bacilli were demonstrated up to the end of the fourth day. 



Similar experiments were performed on the leaf-stalk of a cauliflower. Two infections were 

 made, one (I) on the exposed base of the petiole, the other (II) on the midrib where the blade of the 

 leaf bent over so as to protect the spot from rapid drying. 



The spot (I) which was still somewhat moist, yielded numerous colonies after 24 hours, but none 

 at the end of 48 hours, when it was fully dry. The spot II was tested at the end of 24, 48, 72, and 96 

 hours. Living cholera bacilli were present on it at the end of 24, 48, and 72 hours. They were not 

 demonstrated at the end of 96 hours, and were sparingly present at the end of 72 hours. 



The experiments of Wurtz and Bourges (1901) were undertaken to determine whether 

 the culture of certain vegetables should be forbidden on the sewage fields of Paris. Their 

 technique was as follows: 



Pots were filled with soil and sowed with seeds of cress, lettuce, and radish. Immediately after, 

 the earth was watered with suspensions of the given microbe, taken from agar cultures or potato 

 cultures. Ordinary plate cultures gave no positive results, owing to the prodigious number of colo- 

 nies developing from soil bacteria present on the stems. Only in case of three pathogenic bacteria 

 did they obtain positive results from the tips of the leaves by the use of special methods. 



In three series of experiments with anthrax they obtained cultures from the leaves by first 

 heating them for 3 minutes at 80° C, and then making gelatin plates. The anthrax organism was 

 recovered constantly and easily up to 3 weeks from the time of the sowing. 



The typhoid fever organism was recovered by placing the leaves in ordinary carbolated bouillon 

 at 42° C. for 2 days, after which gelatin plates were poured. With pure cultures from these plates 

 agglutination tests were made. The results were positive in 30 cases out of 30. 



The tubercle organism was detected by inoculating into guinea-pigs fragments of leaves bruised 

 in sterile water. The first series gave i positive result out of 4. The second gave 18 positive results 

 out of 30. 



Experiments with the colon bacillus miscarried. 



These experiments were carried on in the laboratory, at room temperatm-e. The plants were 

 exposed to the sxm only a short time each day, and were not washed by rainfall. Consequently: 



