Artificial Parthenogenesis in Thalassema Mellita 1 15 



phore of about twenty-two hours they are replaced by very short 

 inactive cilia" (p. 190). Compare my Figs. 9 and 10. 



All degrees of abnormality, however, may be seen in the ciliation 

 of the parthenogenetic embryos and larvae. In some cases the 

 apical flagella are entirely wanting or reduced in number, while 

 the cilia on the prototroch may as often fail to form a complete 

 band and appear in irregular clumps or patches, sometimes 

 occurring only on one side ; or they may lose every trace of a band- 

 like arrangement and cover more or less uniformly the whole pre- 

 trochal region of the animal (Figs. 11 and 12). In regard to 

 their activity, they may beat in the same way and with about the 

 same vigor as they do in the normal embryo and larva, producing 

 the characteristic spiral movement of the latter. Associated with 

 abnormalities in form and distribution, their movements may also 

 depart widely from those that are typical and lack all apparent 

 coordination. The enfeebling of the stroke may be so pronounced 

 as to render the cilia incapable of causing any bodily movement 

 of the embryo. I gained the impression that functional derange- 

 ment of the cilia was always correlated with morphological 

 abnormalities of the embryo, and that the farther the embryo 

 departed from the normal in structure, the more erratic were 

 the movements of the cilia. 



As Torrey has described, the embryo is at first entirely separated 

 from the egg membrane, but later through the elevation of the 

 surface in these regions, the rosette and primary prototroch become 

 pressed against the membrane which is then punctured by the 

 cilia (p. 187). In the parthenogenetic embryos, especially when 

 the relations are more nearly normal, the same perforation of the 

 membrane by the cilia takes place. This, however, is not always 

 the case. Sometimes the perivitelline space is so greatly enlarged 

 and the membrane in consequence so far removed from the sur- 

 face of the embryo, that the cilia only touch it at their outer ends, 

 if they reach it at all; or, again, although the membrane may lie 

 close to the embryo, the cilia fail to puncture it and are bent 

 down, being held in this condition until they are released by the 

 rupturing of the membrane (Fig. 13). 



As already stated, the movements of the cilia are usually quite 



