24 SUMMARY OF CUKKKNT 1,'KSKA KCII KS RELATING TO 



cephalothorax, and it does not possess any special absorptive organs for 

 taking up a special kind of food from the host. Nutrition seems to 

 take place by simple filtration from the host's blood through the very 

 thin skin of the parasite. 



The effect of the parasite on the internal genital organs is slight, as 

 compared with the effect of Sacculina on Inachus, and leads to a 

 reduction in the size of the ovaries to about a quarter the normal size, 

 while the testes are usually unaffected. The ovaries of stylopized bees 

 never produce ripe ova, but the testes generally produce normal ripe 

 spermatozoa. The effect on the secondary sexual characters is again 

 slight as compared with that of Sacculina on Inachus. The external 

 gonapophyses are usually unaltered, or they may be slightly reduced in 

 size ; the antennae are unaltered. The scopa of the parasitized female 

 is generally reduced in size, and she never or very rarely collects any 

 pollen. The punctuation on the abdomen of the male maybe increased. 



The most striking effect occurs in certain species (e.g. Andrena 

 labialis and A. chrysosceles) in which the male normally has a yellow 

 clypeus and the female a black one. Stylopization in those cases may 

 lead to the female assuming a yellow clypeus as in the male, while the 

 male may lose the yellow and acquire a partially black clypeus. This 

 acquisition of the yellow clypeus by the female is the only change 

 which can undoubtedly be interpreted as a positive acquisition of a 

 secondary sexual character proper to the opposite sex. This effect may 

 be brought about by male or female Stylops indifferently, the sex of the 

 parasite having nothing to do with the nature of the effect exerted. 



The effects of stylopization may be ascribed to a merely quantitative 

 abstraction of nutriment from the gonad, leading to its partial atrophy, 

 and not to a qualitative alteration of the metabolism such as is brought 

 about by Sacculina. This also applies to the assumption of the yellow 

 clypeus by stylopized females, or the analogy of the assumption of male 

 plumage by many female birds as the result of simple ovariotomy or 

 ovarian atrophy. 



Chromosome Complex of Culex pipiens.* — Monica Taylor finds 

 that the somatic number of chromosomes in the gnat is three, in both 

 sexes. The number of chromosomes in the spermatogonia as well as in 

 the primary and secondary spermatocytes and spermatids is three. 

 The spermatogonial cells are not characterized by a synizesis stage. A 

 synizesis stage marks off the spermatogonial from the first spermatocyte 

 stage. The nuclear membrane persists throughout mitosis. The 

 synizesis stage represents an inactive phase of the nucleus in spermato- 

 genesis. A synizesis stage occurs in somatic nuclei. 



Narcissus Flies. f— Of the various animal pests attacking the bulbs 

 of Narcissus and related plants none are more injurious than the flies — 

 Merodon equestris and Eumerus strigatus, known as the large and the 

 small Narcissus fly. The first is like a hive-bee or drone-fly (Eristalis). 

 The eggs are laid near the base of the leaves or on the necks of the bulbs ; 



* Quart. Joum. Micr. Sci., lx. (1914) pp. 377-98 (2 pis. arid 3 figs.), 

 t Board of Agriculture Leaflet No. 286 (1914) pp. 1-6 (1 pi.). 



