376 



SCIENCE. 



[N. S. Vol. XX. No. 507. 



THE SONG OF BIRDS. 



In view of tlie interest attached to the ex- 

 periments made by Professor W. E. D. Scott 

 with a view to ascertaining whether the song 

 of birds is instinctive or imitative it may be 

 well to recall that very similar experiments 

 were made Over a century ago. Wallace notes 

 in his essays on ' Natural Selection, etc.,' that 

 " The Hon. Daines Barrington was of the 

 opinion that ' notes in birds are no more in- 

 nate than language is in man, and depend 

 entirely on the master under which they are 

 bred, as far as their organs will enable them 

 to imitate the sounds which they have fre- 

 quent opportunities of hearing." An account 

 of his experiments is given in the Philosoph- 

 ical Transactions for ITTS, Vol. LXII., and 

 his results were practically the same as those 

 obtained by Professor Scott, the young birds 

 acquiring the song of their foster parents and 

 not the notes of their own species. Barring- 

 ton notes that the birds must be taken from 

 the nest when very young, as they are apt 

 pupils and learn the call notes of their parents 

 at an early age. 



P. A. L. 



Museum of the Brooklyn Institute, 

 August 28, 1904. 



doctorates and fellowships. 

 To THE Editor of Science: In Science for 

 August 19 is the remark : 'It is somewhat 

 surprising that California and Stanford have 

 together conferred the degree (of Ph.D.) but 

 twenty-five times in seven years.' Among the 

 reasons for this are two : the authorities of 

 this institution advise their advanced students, 

 for the sake of breadth of experience, to take 

 a part of their work in the east or in Europe. 

 This is generally the concluding part. On 

 the other hand, the California institutions 

 grant few artificial aids to students as such. 

 At Stanford this is regarded as a matter of 

 principle, tuition being free to graduate stu- 

 dents. By the wider introduction of the 

 ' trading stamp system ' in higher education, 

 the number of degrees could be greatly in- 

 creased, but with no gain to science or art. 



David Starr Jordan. 



SPECIAL ARTICLES. 



limitations of the klinostat as an instru- 

 ment for scientific research. 



The klinostat is an instrument used mostly 

 in plant and animal physiology, revolving 

 about either a vertical or a horizontal axis, 

 for the purpose of neutralizing the tropic 

 (curving) effects of light and gravitation. It 

 was first made practical and introduced into 

 laboratory work by Sachs in 1872, and fully 

 described with additional improvements in 

 several papers in that memorable series of 

 pioneer research entitled ' Arbeiten des bo- 

 tanischen Instituts in Wiirzburg.' 



The instrument as commonly manufactured 

 is actuated by springs, and may be given sev- 

 eral speeds, usually one revolution in ten, 

 fifteen, twenty or thirty minutes. In the use 

 of the instrument for demonstration and re- 

 search during the past thirty years, it has gen- 

 erally been thought immaterial to consider 

 the angles at which plants are secured to the 

 horizontal klinostat for the purpose of neutral- 

 izing the tropic effect of gravitation, or to 

 consider the distribution of light when plants 

 are revolved on the vertical klinostat for the 

 purpose of neutralizing the tropic effect of 

 light. In addition to the foregoing relations 

 of the instrument to gravitation and light, 

 the present tendency to substitute electric and 

 water motors for springs to drive the machines 

 introduces relations of speed. The research 

 of the past ten years has indicated very im- 

 portant limitations to the use of the klinostat, 

 and the most general of these are pointed 

 out in the following lines, and should be recog- 

 nized by every one using this instrument. 



Evenness of Speed. — The first requisite for 

 securing evenness of revolution is the center- 

 ing of the load. An excentric load will give 

 a slower speed periodically, and this will bring 

 curves. It has been shown in my own labo- 

 ratory that, in a speed of one revolution in ten 

 minutes, a periodic retardation of but a second 

 or two, due to excentricity of load, will cause, 

 after a long interval, a geotropic curve by the 

 summation of stimuli. 



Avoidance of Centrifugal Effect. — ^It is well 

 known that -in rapid revolution, plants simu- 

 late toward the so-called centrifugal force 



