142 J. F. MCCLENDON. 



them and allowed to remain until the water rose in it as high as 

 it would by capillarity. The dish was moved until an egg of the 

 most favorable orientation was brought in the center of the field. 

 The capillary tube was then brought against the proper spot on 

 the egg and a portion of the egg sucked away through the tube 

 (<:) which was held in the mouth. Immediately the operated egg 

 was lifted from the dish by means of a capillary pipette just large 

 enough to admit it easily, and placed in a watch glass half full 

 of sea water. This capillary pipette does not need a bulb, as 

 water enters it by capillarity. The size of the capillary end ot 

 the tube (&) was determined for the egg of each species by trial 

 Some parts of the mechanical stage were an unnecessary hind- 

 rance and were removed. 



EXPERIMENTS ON THE EGGS OF CH^TOPTERUS PERGAMENTACEUS 



CUVIER. 



Mead ('gS 2 ) and J. Loeb ('01) found that differentiation went 

 on in the unfertilized egg of Chcstoptervs in solutions of KC1, and 

 F. R. Lillie showed that this differentiation bears a semblance 

 to the normal development save that cell division is usually 

 suppressed. 



I removed the chromosomes during the maturation divisions 

 of the unfertilized egg in KC1 solutions by sucking away the part 

 of the egg immediately under the first polar body, in order to 

 determine the effect of the chromatin on differentiation. A small 

 percentage of eggs were so injured by the operation that they 

 remained inactive until disintegration. Others, however, per- 

 formed those " amceboid " movements which Loeb mistook for 

 cleavage, just as in operated eggs. Further than this no changes 

 were visible externally, but sections showed that irregular flow- 

 ing of substances had taken place within the egg. None of the 

 operated eggs developed cilia, and we might conclude that the 

 chromatin is necessary for the formation of cilia, a function that 

 has been attributed to the archoplasm. But as the centrosomes 

 were probably removed with the chromosomes, and as the ele- 

 ment of injury could not be excluded, this negative evidence 

 should not be considered conclusive. Nearly one hundred eggs 

 were operated on, and, although I do not think it advisable to 



