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THE AMERICAN NATURALIST [Vol. XLII 



must be briefly described. It appears as a minute body in the 

 situation previously occupied by the central spindle of the final 

 mitosis, and consequently far removed from the blepharoplast, 

 which lies m ar the polar region of the spindle, with the nucleus 

 between them. This structure is the "Nebenkern" of other 

 authors. The " Nebenkern" later occupies various situations in 

 the cell, but always remains as a small structure and does not 

 enter into the construction of the spiral body of the sperm; it 

 finally comes to lie in the cytoplasm which becomes attached, as a 

 vesicle, to the posterior coil of the mature sperm. 



Yamanouchi's results on Xephrodium are opposed to those of 

 Belajeff for Marsilia, who holds that the blepharoplasts like 

 centrosomes occupy the poles of the spindle and are derived from 

 centrosomes in a previous mitosis within the antheridium. The 

 account agrees with Webber's conclusions for Zamia that the 

 blepharoplast arises de novo in the cytoplasm, and also with 

 Shaw's view for Marsilia that the blepharoplast has no genetic 

 relation to the pole of the spindle in the final mitosis. 



It seems probable that the centrosome theory of the blephar- 

 oplast, as held by Belajeff, Ikeno and others, has placed undue 

 emphasis on the proximity of the blepharoplasts, in the types 

 studied, to the poles of a closely associated mitosis. There are 

 no mitoses present during the entire period of zoospore formation 

 in Derbesia, which consequently offers important evidence 

 against this view. Since similar conditions are also present 

 during zoospore formation in CEdogonium and a number of other 

 algae, the investigation of these types is likely to prove very 

 interesting. The blepharoplast unquestionably gives a marked 

 polarity to the cell but it has not yet been established that this 

 polar organization is derived,- as such, from the immediate cell 

 progenitors, however pleasing, for theoretical reasons, would be 

 the establishment of such a history. 



Bradley M. Davis. 



ORNITHOLOGY 

 Riddle on the Genesis of Fault-bars and the Cause of Alternation 

 Light and Dark Bars in Feathers. 1 — In a much shorter paper 

 'Riddle, Oscar. The Genesis /f Fault-bars in Feathers and the Cause 

 Alt, rim,,,,, of Light and Dark Fundamental Bars. Biological lun. 

 XIV ' No - 6 » M *y, 1908, pp. 328-370, pis. xii-xv. 



