614 MAECUS M. HARTOG. 



Fertilisation " from giving any explanation of his own ; but in 

 the preceding one he suggests that " we may always suppose 

 that a reduction in the quantity of material elements may act 

 with effect on molecular forces, attenuating their strength and 

 giving more delicacy to their play." Now, what we know of 

 molecular forces would be rather in favour of the view that 

 reduction of the masses would give more energy and violence 

 to the action of the nuclei. He is clearly right in rejecting 

 all explanations of " polar bodies " which are inapplicable to 

 the three preliminary mitoses of the micronucleus of the 

 infusorian gamete.^ Probably the phenomena are essentially 

 morphological, a question which will be discussed in my paper 

 on " Some Problems of Reproduction." 



In the above abstract many interesting points have been 

 left untouched ; much has been treated far too summarily. 

 But I trust that I have given an idea of the value and wealth 

 of the papers, and brought out their two cardinal points : the 

 limits of reproduction by continuous fission alone; and the 

 nature and results of conjugation. 



* A singular omission from this discussion is that Maupas nowhere brings 

 in his discovery that certain brood-nuclei of the rejuvenated conjugation- 

 nucleus itself abort as "noyaux de rebut," instead of becoming mega- or micro- 

 nuclei. 



