30 HISTORY OF THE EGG FROM FERTILIZATION TO CLEAVAGE. 



(No. 12), we have one of the most remarkable examples yet placed on 

 record of ascendency on the part of the nr.de pronucleus. The female 

 pronucleus does not arrive on the scene of action until the two poles of 

 the cleavage amphiaster are widely separated and the male pronucleus 

 lias undergone the spindle elongation. Vejdovsky is inclined to the opinion 

 that the female pronucleus plays a merely passive role, being probably 

 absorbed by the male pronucleus. But there are not wanting most sus- 

 picious indications that this view contains only half the truth. Why not 

 both pronuclei equally passive? If the periplast is the seat of activity. 

 possibly the male pronucleus has no advantage over the female, unless it 

 be first to fall under the influence of the periplast centres. In the light 

 of what is now known, there is little room to doubt the equal division 

 and distribution of the chromatic elements of both pronuclei, even in 

 the face of such adverse-looking facts as Vejdovsky has pointed out in 

 Rhynchelmis. It is to be hoped that Vejdovsky will soon be able to trace 

 the anomalous history of the female pronucleus to its end. for its eluci- 

 dation promises to be an important addition to our knowledge of fecun- 

 dation. The appearances, so far as they go, certainly favor the view 

 that the nuclear functions are monopolized by the male pronucleus ; 

 but an idea so entirely revolutionary as this, upsetting so many theories 

 of caryokinesis, heredity, etc., cannot be seriously entertained, until cur- 

 rent hypotheses are shown to be clearly incompatible with the facts. 

 As the case now stands, it is by no means impossible that the chromatic 

 elements of the female pronucleus, belated though they may be. eventu- 

 ally fall into the usual line of march, taking their equal share in the 

 formation of the nuclear plates. This is the position we are compelled 

 to take while waiting further discoveries. 



0. Caryologieal Terminology. — In the present unsettled state of views 

 concerning caryokinetic phenomena, the simplest nomenclature is un- 

 doubtedly the best. Fortunately the terms already in use are sufficient 

 for present needs, and we have little more to do than to make a choice 

 among current synonyms. It is not our intention to review the systems 

 proposed by Flemming, Carnoy, and others, but merely to indicate briefly 

 such preferences as our work has suggested. 



We find no occasion to adopt such terms as eyto- and caryo-diceresis 

 (Carnoy) as substitutes for cell and nuclear division. Caryokinesis (Schlei- 

 cher) is preferred to caryomitosis (Flemming), as the latter term is restricted 



