Manchester Memoirs, Vol. I. (1906), No. 0. 7 



■nucleus with the second polar nucleus i^Figs. 1 1-14). The 

 process of polar nuclei formation is otherwise similar to 

 that of the previous species. They may take up positions 

 farther apart. They move towards the periphery of the 

 ^^% and in P. luteoluin degenerate, or the products of the 

 first polar nucleus degenerate and the second becomes 

 resolved into chromosomes. It is also found that the 

 number of the chromosomes in the yolk nuclei, which are 

 derived from the egg-nucleus, remain at the maturation 

 number, as far as can be followed, that is to the forma- 

 tion of the blastoderm. Doncaster does not, with 

 Petrunkewitsch, fall back on the theory of Weismann, 

 that every ovum possesses a power of growth sufficient 

 to double its nuclear substance, but thinks that there is 

 no reduction, as in Rhodites rosae. This conclusion is only 

 provisional, and it cannot be definitely decided until the 

 oogenesis and spermatogenesis have been worked out. 



FORMICID.-E. 



Lasius niger. The maturation of the unfertilised ovum 

 of this arrhenotokous ant has been studied by Henking(44). 

 He found that three polar nuclei were formed. At one stage 

 there is a fusion of the inner half of the first polar nucleus 

 with the second polar nucleus to form a syntelosome, this 

 stage being very similar to that which he found in the 

 maturation of the fertile ovum {cf.figs. 327, 259). Later 

 he observed a dissolution of these nuclei. In a further 

 stage he observed a scattered mass of chromatin bodies, 

 which he considered to have been formed from the polar 

 nuclei, in the peripheral cytoplasm of the &^'g. Their fate 

 is unknown ; their resemblance to the mass of cells result- 

 ing from the sub-division of the syntelosome in the bee 

 is striking. 



