672 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Spermatogenesis of Honey Bee.* — L. Doncaster re-describes the 

 final maturation division regarding which his previous account erred. 

 In the anaphase there are 16 very small chromosomes at each end. 

 When the spindle is formed, 16 chromosomes arrange themselves in the 

 equatorial plate in such a way that they are generally closely associated 

 together in pairs. It may sometimes be seen that each individual 

 member of the pair is in itself double or dumb-bell shaped, and when 

 the division takes place the members of a pair are not separated from 

 one another, but each divides so that the 16 halves pass to each pole. 

 These results are in essential agreement with those of Mark and 

 €opeland. 



Gametogenesis and Fertilisation in Nematus ribesii.j — L. 

 Doncaster thus summarises the results of his investigations. True 

 fertilisation (conjugation of male and female pronuclei) may take place 

 in N. rihesii, and the behaviour of the polar nuclei is sHghtly different 

 in fertilised and virgin eggs. In the spermatogenesis there are eight 

 chromosomes in spermatogonial divisions ; four gemini appear at the 

 beginning of the maiotic phase, and by heterotype and homotype 

 mitoses "distribute four chromosomes to each spermatid. In the 

 oogenesis eight chromosomes appear in oogonial mitoses, but in divi- 

 sions of nuclei in the ovary-sheath more than eight are found, suggesting 

 that the chromosomes of the germ-ceUs are compound. In the polar 

 mitoses of the egg two types of maturation are found. In some eggs 

 there are successive equation divisions, so that the egg nucleus and each 

 of the three polar nuclei contain eight chromosomes. In other eggs 

 normal reduction takes place, separating entire chromosomes from one 

 another, and only four are found in each of the daughter-nuclei. It is 

 probable that only such reduced eggs are capable of fertihsation, but 

 when unfertilised they may continue to develop at least as far as the 

 blastoderm stage. 



Variation in Parthenogenetic Insects. | — Vernon L. Kellogg has 

 utilised drones (parthenogenetically produced) and worker honey bees (of 

 bisexual parentage), also female aphides (parthenogenetically produced) 

 to test the value of amphimixis in causing variations. With regard to 

 the bees in all but one of the characteristics studied, the amount of 

 variation, both quantitative and qualitative, is markedly larger aruong 

 the drone bees than among the workers, and in the one exceptional 

 characteristic it is no less. No more variation in wing characters ^s 

 apparent among drones or workers that have not been exposed in 

 imaginal condition to the rigours of personal selection, than exists among 

 bees, drones, or workers that have been so exposed. The variation in 

 wing characters in drone bees reared in worker cells is no greater than 

 that among individuals reared in drone cells. The variation among 

 drones hatched from worker-laid eggs is markedly larger than that 

 among drones hatched from queen-laid eggs (the drones of worker 

 parentage are considerably smaller than those of queen parentage). In 



* Anat. Anzeig., xxxi. (1907) pp. 168-9. 



t Quart. Journ. Micr. Sci., li. (1907) pp. 101-13 (1 pi.). 



X Science, xxiv. (1906) pp. 695-9. 



