ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 179 



■melolonthise, and Metalnikow has done the same with the caterpillars of 

 OalJeria into which were injected Bacillus perfringens, B. siibtiUs, 

 B. proteus, and Pneumococcus. In these cases of acquired immunity a 

 chaiio'e is produced in the activity and sensitiveness of the phagocytes. 



J. A. T. 



Two Parasites of Blow-flies. — A. M. Altson {Proc. Zool. Soc. 

 London, 1920, 195-243, 20 tigs.). A Braconid Hymenopteron, Alysia 

 maiiducator Panz., oviposits in the larvse of several carrion-feeding 

 Diptera. Only one parasite emerges from one host puparium. Over- 

 parasitism kills the larva. The mean-average of the life-cycle is 52 days, 

 the shortest is 25. Both sexes are capable of sustained flight, and they 

 lived over a month in captivity. Another Hymenopteron, a Chalcid, 

 Nasonia brevicornis, oviposits in the puparia of several species of 

 stercoral and carrion-feeding Dipterous larvae. From 1 to 62 have been 

 found in one puparium. The length of the life-cycle varies from 

 11 to 22h days in different countries. Only the females can fly, and 

 then only for short distances. They can live, whilst ovipositing, for 

 4 to 6 weeks, but for a considerably less period without host puparia. 

 The males remain near the place of emergence, fighting and matiog. If 

 and when puparia containing .1. jnanducator are within reach of Nasonia, 

 the latter may act as an accidental secondary parasite on the former. 

 Both parasites when hil)ernating as full-grown larvte can withstand over 

 6 weeks at 2'' C. Both check flies — Alysia more effective against tlie 

 Blow-fly, Nasonia more effective against the House-fly. J. A. T. 



Eg-g-laying- Reactions in Pomace-fly. — Edward F. Adolph 

 {Jovrn. Exi^er. Zool., 1920, 31, 327-41). Single stimuli do not call 

 forth any considerable amount of egg-laying in Drosophihi. When 

 odours and textures are properly combined, the fly may lay nearly as 

 many eggs as in natural conditions. The presence of moisture charac- 

 terizes all conducive complexes. The most stimulating substances are 

 known to occur in the natural food material of the fly, e.g. odorous sub- 

 stances. A slight amount of egg-laying takes place under the simplest 

 conditions, but a large amount requires a complex. The only intei'nal 

 condition of importance is sexual maturity, but mating, nutritive 

 condition, and internal periodicities seem to have some influence upon 

 the production of eggs. J. A. T. 



Bristle Inheritance in Drosophila. — Edwin Carleton MacDowell 

 [Joura. Exper. Zool., 1920, 30, 419-60, 8 figs.). The early generations 

 of a race of Drosophila that was continuously selected for increased 

 bristle numbers during forty-nine generations show higher correlation 

 coefiicients than any others. AVith the greatest uniformity of the en- 

 vironment, the last thirteen generations show no correlation at all A 

 final test of the germ-plasm of the selected race was made by raising 

 four more generations without selection. In generations 52 and 58, 

 31,000 bristle counts indicated that the higher-grade parezits did not 

 ■produce higher-grade offspring. No evidence of sex linkage was found. 

 The difference between the sexes is interpreted as due to general 

 developmental conditions initiated by the sex chromosomes, rather than 

 to the linkage of a specific gene. The correlation method supports 



