350 



SCIENCE 



[N. S. Vol. XLII. No. 1080 



mitochondria in the cells of the chick embryo 

 increase in size and divide by fission, when 

 the cells are grown in vitro. If, as my obser- 

 vations indicate, mitochondria are involved in 

 the anabolic phase of metabolism, one would 

 expect them to grow in the cell of the chick 

 embryo by accretion from end products of 

 digestion absorbed by the cell; whereas in the 

 amphibian embryo the food is stored within 

 the cell as relatively stable substance and the 

 whole transformation from food to protoplasm 

 must take place in situ. So long as the cell is 

 nourished from yolk which it contains, the 

 mitochondria, I believe, grow upon the surface 

 of the yolk globule. They may be certain end 

 products of digestion, or they may be synthe- 

 sized out of certain of the end products of 

 digestion. However, before accepting this 

 hypothesis it is important to know whether 

 ilnitochondria occur in cells which have been 

 deprived of their yollt by centrifuging. The 

 work of Banta and Gortner,^ and particularly 

 that of Jenkinson,^ upon the development of 

 centrifuged amphibian eggs should be ex- 

 tended into the cytological field to determine 

 wherein the mechanism is deficient in those 

 cells which do not develop normally. Further- 

 more, the interpretations here offered, in so far 

 as they relate to mitochondria, must be quali- 

 fied by the consideration that their validity 

 rests largely upon the nature of the bodies in 

 the protoplasms which I have regarded as 

 mitochondria. My judgment on this point is 

 based upon the use of janus green as a vital 

 stain and of Bensley's aeetic-osmic-bichromate 

 method, the two methods which, taken to- 

 gether, seem to be accepted as the nearest ap- 

 proximation to a specific test for mitochondria 

 now at our command. But regardless of 

 theoretical considerations, the observations 



■f Banta, A. M., and Gortner, E. A., "Accessory 

 Appendages and Other Abnormalities Produced 

 in Amphibian Larvas through the Action of Centrif- 

 ugal Force," The Journal of Experimental Zool- 

 ogy, Vol. 18, No. 3. 



8 Jenkinson, J. W., ' ' The Eelation between the 

 Structure and the Development of Centrifuged 

 Eggs of the Frog, ' ' Quarterly Journal of Micro- 

 scopical Science, April, 1914. 



which have been described are, I believe, sub- 

 stantially correct, and they are presented in 

 this form with the hope of stimulating in- 

 terest in a field of study which affords peculiar 

 opportunity for making a definite advance in 

 our knowledge of the mechanics of the cell, 

 particularly in relation to the growth of the 

 organism. 



George E. Coghill 

 Universitt of Kansas 



trains op beating light waves 



If two spectra, having the same longitudinal 

 axis but reversed in color {i. e., respectively 

 red-violet and violet-red), are brought to inter- 

 fere, the interference should occur only along 

 the single transverse line of coincidence and 

 therefore be inappreciable. If it is visible, 

 then light waves of slightly different wave- 

 lengths, lying symmetrically on either side of 

 the common transverse axis, must also be capa- 

 ble of interference in optics, in complete anal- 

 ogy with the case of musical beats in acoustics. 

 After long searching I found that the occur- 

 rence of the phenomenon in question can be 

 shown experimentally. Its scintillating ap- 

 pearance is exceedingly striking. It is com- 

 plete within a transverse strip of the spectrum 

 but one half to one third the width of the 

 sodium lines. It partakes of the general char- 

 acters of elliptic interferences however, except 

 that the ellipses are now extremely eccentric 

 (needle-shaped in other words) and confined to 

 a single color. If the given width be regarded 

 as the distance between two fringes and esti- 

 mated as rfX^ 2.4 X 10'* cm., if x be the dis- 

 tance along the axis of propagation within 

 which one reenforcement occurs, then 



x. — \-/d\ — Z6 X 10-'V2.4 X 10-' =.15 cm., 



or the limiting group wave-length of the light 

 waves is over a millimeter. Details and allied 

 results, for which there is no room here, will be 

 found in the complete paper, now in the hands 

 of The American Journal of Science. 



Carl Barus 



Brown University, 

 Providence, E. I. 



