38 SUMMARY OF CUURENT RESEARCHES RELATING TO 



through the bulb into the vagiua. The alternate contractions of circular 

 and longitudinal muscles of the seminal vesicles and accessory glands 

 bring about ejaculation — first of the sperms only and then of mucus. 

 The queen breaks off the everted copulatory organ, usually close behind 

 the bulb, by crawhng or flying in a circle round the drone, and returns 

 with it to the hive. It becomes dislodged or is pulled away by the bees 

 in the hive within a few hours. The mucus is absorbed in the oviduct ; 

 -the sperms pass by the sperm-duct to the spermotheca. J. A. T. 



Nest of Solitary Wasp, Crabo cephalotes.— Cecil VVarburton 

 {Proc. Camhridye I'hil. Soc, 192<t. 19, 21)0-8). Observations on a small 

 colony in a log of elmwood kept in the author's garden at Cambridge 

 as an example o'f a woodpecker's nest. The cavity was gradually filled 

 with the " sawdust " of the burrows in the wood. C^onspicuous on the 

 sawdust were numerous Syrphid flies, especially Syrphm balteatus, used 

 as food. There was no attempt to seal or mask the tunnels. There 

 was nothing to prevent any enemy from entering. The main tunnels 

 were clear, and penetrated the wood for several inches, with abrupt 

 turnings on no definite plan. From these proceeded side galleries in 

 which were found " sawdust," the debris of flies, and the brown cocoons 

 containing the fully-fed wasp larvae. J. A. T. 



Inheritance of Silkworm Characters.— Maude L. Cleg-horn {Proc. 

 Zool. Soc, 19LS, 138-46). The inheritance of the visible colour 

 character of the cocoons is clearly Mendelian. The inheritance of the 

 invisible univoltine and multivoltine character (dominant when inherited 

 by the females, recessive in males) does not appear to be quite Mendelian, 

 but it may be that the sex-limited descent affects the inhei'itance. and 

 that there is really no failure in segregation of the unit characters. 



J. A. T. 



Origin of 6ynandromorphs.~-T. H. Morgan and C. B. Bridges 



{Puhlication 278, Carnegie Inst. Washin/jton, 1919, 1-122, 4 pis., 

 70 figs.). A study of gynandromorphs (combining male and female 

 characters, it may be both gonadial and somatic) in Drosophila meJano- 

 gaster, on which numerous experiments have been made. Many of the 

 gynandromorphs were hybrids of known sex-linked characters, i.e. 

 characters whose genes are carried by the sex chromosomes. By adding 

 to such crosses additional characters whose genes lie in other than the 

 sex chromosomes, it has been possible to prove that the male and female 

 parts of the gynandromorph differ l)y the sex chromosomes alone, i.e. 

 both male and female parts contain the same autosomal group. It was 

 possible, in consequence, to show that these gynandromorphs are not 

 due to partial fertilization (Boveri), or to polyspermy (Morgan), but to 

 chromosotnal elimination (Morgan). Chromosomal elimination means 

 that at an early stage in embryonic development one of the daughter 

 chromosomes of one of the X's fails to pass over to one of the daughter 

 plates, and accordingly gets left out of that nucleus. In consequence, 

 one of the two cells will contain only one X chromosome, and produce 

 male parts, while the sister cell with two daughter X chromosomes will 

 produce female parts. The evidence that elimination of this kind takes 

 place rests on cases in which the X chromosome derived from the father 



