Septembee 4, 1896.] 



SCIENCE. 



317 



But a more important question to determine, 

 and one about which much less is definitely 

 known, is the height at which these night-flying 

 birds migrate. Both Messrs. Scott and Young, 

 and Mr. Tatlock and myself, solved this problem 

 by a hypothetical assumption of the inferior and 

 superior distances at which a bird would be 

 visible. In this way we arrive at the conclu- 

 sion that the birds seen were between one and 

 three miles above the earth. There is much 

 confirmatory evidence of the truth of this sup- 

 position. For instance, Mr. E. A. Bray rec- 

 ords in Nature (Vol. 52, p. 415) a flight of birds 

 observed by him through a telescope directed 

 toward the sun, at 3 p. m., on September 30, 

 1894, at Shere, Guilford, England. The birds 

 were invisible to the naked eye, but must have 

 been at least two or three miles away, as both 

 birds and sun were in focus. 



Additional observations are needed, however, 

 before this matter can be considered as satis- 

 factorily settled. If, by experiments made dur- 

 ing the day, the observer can ascertain with 

 exactness the lesser and greater distances at 

 which a bird would be visible through a glass 

 focused on the moon, and the appearance of a 

 bird at a known distance, he would then have 

 established some basis for comparison [of the 

 observations made at night. 



It is also of importance to note the time oc- 

 cupied by the bird in crossing the moon's face. 

 This varies greatly ; some birds appearing as a 

 mere flash of wings, while others are silhouetted 

 against the moon with great distinctness, and 

 are in the field for several seconds. 



Assuming that small birds migrate at the 

 rate of about forty miles an hour, and that they 

 pass through the field at right angles to the line 

 of vision, we have here a means of determining 

 approximately the width of the angle at their 

 point of crossing and consequently, in connec- 

 tion with the moon's elevation, their height 

 above the earth. 



Frank M. Chapman. 



American Museum of Natural History. 



curious freak in an apple tree. 

 Some very curious apples were found last 

 year in an orchard about a mile north of Lake 

 Erie. The apples on the northeast side of a 



certain tree were Ehode Island Greenings, such 

 as the tree had always borne, while those on 

 the southwest half of the tree were of a mixed 

 character, each apple being partly Greening 

 and partly Talman Sweet. 



The different kinds occurred in sections, for 

 the most part corresponding to the carpels. 

 In some, three sections or three-fifths were 

 Greening and two-fifths Talman Sweet, while in 

 others the proportions were reversed. In 

 others one-fifth was Greening or Talman Sweet, 

 and in others again the proportion of Talman 

 Sweet was still less. 



The different parts were in most cases easily 

 distinguished by color and by the greater pro- 

 tuberance of the Greening as forming part of a 

 larger apple. The flavor of the parts was as 

 purely Greening or Talman Sweet as if they 

 had belonged to separate apples on separate 

 trees, except where the two came together. 



The line of demarkation between the parts, 

 though not very definite, corresponded in most 

 cases with the divisions between carpels, and 

 ran from base to summit, except that a small 

 part round the summit seemed in all cases to 

 be Greening. Sometimes a portion of Talman 

 Sweet was found wedged in at the base of a 

 segment, extending only about half way to the 

 summit. 



A short distance to the southwest of this tree 

 stands a Talman Sweet tree ; and there can be 

 no reasonable doubt that the phenomenon arose 

 from cross-fertilization between the pollen of 

 the Talman Sweet and the ovule of the Green- 

 ing, It is difficult, however, to see why the 

 pollen, which acts directly upon the ovule, 

 should so profoundly affect the receptacle and 

 calyx, which make up the fleshy part of the 

 apple. Equally difficult is it to understand 

 why cross-fertilization, which must frequently 

 occur in apple trees, should in one instance pro- 

 duce mixed fruits, and in a thousand cases 

 produce no appreciable effect whatever. Per- 

 haps some of the readers of Science can throw 

 light upon the subject. 



T. H. Lennox. 



Woodstock, Ont. 



I HAD the privilege of examining samples of 

 the apples of which Mr. Lennox writes, and 



