RELATED STUDIES AND CRITIQUES. 175 



constitutes the attraction of this organ. Since a single petal or a bud 

 deprived of its calyx exerts this attraction, it can not depend upon the form 

 of the flower. Hence, it must be due to the color, which must also stand 

 out sharply from the background to the bee's eye, although it can not 

 be said that they see the color red as we do. Small amounts of honey had 

 relatively little effect, at equal distances a single corolla exercising a much 

 stronger power of attraction than a quantity of honey much greater than 

 that ever found in a single flower. 



Response to color and odor by a hawk-moth. — The experiments 

 performed by Gorka (1900:57), though few in number, are among the most 

 important of all, as they were carried out with newly hatched moths in 

 which either the antennse or the eyes were rendered useless. He noted that 

 Deiliphila elpenor, which was frequent in a garden in upper Hungary, 

 sought the flowers of Phlox paniculata and drummondi with especial fond- 

 ness, but ignored the other flowers, such as Dianthus, Malva, Borrago, 

 etc. As a preliminary test, a butterfly was released from its pupal case, 

 when it flew straightway to Phlox. On this he based his experiments to 

 determine whether this flower attracted hawk- moths by means of its color 

 or its fragrance. For this purpose he had at his disposal about 40 pupae. 

 The antennae of three hawk-moths that had just emerged were covered with 

 collodion and thus deprived of the sense of smell. These were freed in the 

 evening, when they flew directly to the Phlox at a distance of about 2 meters 

 and at once began to suck the nectar. Four days later the eyes of 4 hawk- 

 moths just hatched were covered with shellac, but the antennae were not 

 disturbed. In the evening when released, these flew to the flowers of 

 Borrago and Malva, which they immediately left; they finally landed on 

 those of Phlox, where they remained for some time. They then flew away, but 

 only to return for six different visits. These two experiments were repeated 

 12 times, and always with the same results. In three cases the blue flowers 

 of Borrago were sprinkled with essence of jasmine, when it was found they 

 were no longer disdained, but were visited by several of the moths. 



Gorka's results prove conclusively that the hawk-moth is guided by both 

 sight and smell, and indicate that the former is more directive at a distance. 

 Taken in conjunction with the similar experiments of Forel (p. 140), and 

 Mayor (p. 159), they afford convincing evidence of the importance of both 

 senses in regard to attraction. 



Vexillary nature of the plume in Muscari. — In order to test the 

 value of Plateau's conclusion as to the role of vexillary organs, Ferton 

 (1901:96) mutilated racemes of Muscari comosum by removing the sterile 

 flowers, which form a vivid violet-blue plume at the top of the inflorescence. 

 The fertile flowers are brownish and rather inconspicuous, but they emit a 

 pleasant fragrance. Andrena vetula flew indifferently to the fertile or sterile 

 portion of normal clusters, but when the fertile flowers were cut off, it went 

 to the sterile plume direct, then dropped to the level of the fertile ones, 

 only to find them gone. It twice hovered for some time before the muti- 

 lated stem, and also visited two or three such clusters in succession. Bom- 

 bylius fimbriatus likewise went to the vivid sterile group first and then 

 descended slowly along the stem, with the ligule extended, but finally dis- 



