114 SUMMARY OF CURRENT RESEARCHES RELATING TO 



disease in bees. The parasite is not always present in "crawling" bees ; 

 its presence does not always produce the disease ; stocks heavily infected 

 may live long. 



John Anderson and John Rennie* give a detailed account of 

 observations and experiments bearing on Isle of Wight disease in bees. 

 So far they have been unable to recognize any causal relation between 

 the presence of Nosema apis and the disease. They have found the 

 parasite present over prolonged periods in healthy stocks, while they 

 were unable to find it in other stocks in the apiary, nor did Isle of 

 Wight disease spread under these conditions, although various races of 

 bees w^ere present. Deliberate infection of a stock with Nosema did 

 not produce the disease. In numerous cases on Deeside the disease 

 occurred, but the parasite could not be found. The parasite is present 

 in many healthy bees. It may be a contributing factor, favouring in 

 certain cases the development of the disease, but the facts do not point 

 to its being the essential factor. Isle of Wight disease is probably 

 infectious and associated with a parasite, but it does not seem to develop 

 without the coincidence of other and at present unknown factors. The 

 disease is not necessarily conveyed by mere contact with contaminated 

 hives or combs, or by feeding upon contaminated stores. 



Maturation and Fertilization in Platyg'aster.j — F. Silvestri has 

 studied the maturation, fertilization, and early development of Flatygaster 

 dryomyiae Silv., a Proctotrupid Hymenopteron. The first embryonic 

 cell is to be distinguished from an adjacent nucleus which is due to a 

 fusion of the nucleus of the proximal half of the first polar body 

 with that of the second polar body. Round about the first embryonic 

 cell, the fused nuclei alluded to, and the nucleus of the distal half of 

 the first polar body, there is the rest of the ooplasm, the polar part of 

 which forms the trophamnion. What Silvestri has observed in Platy- 

 gaster confirms what he has previously described in various parasitic 

 Hymenoptera of the family Chalcididte. 



Development of Hive-bee. $ — J. A. Nelson has given a full account 

 of the development of this type, and his work will also serve as an 

 introduction to the study of the development of insects in general. The 

 total period normally required for the development of the egg is seventy- 

 six hours. Cleavage occupies fourteen to sixteen hours, blastoderm 

 formation fourteen to sixteen hours ; formation of the mesoderm, 

 rudiments of mesenteron and embryonic envelope twelve to fourteen 

 hours ; and the remainder of development thirty-two to thirty-six hours. 

 The bee-embryo has twenty-one segments including the telson ; no 

 abdominal appendages were seen ; separate coelomic sacs are not present, 

 the somatic and splanchnic layers of mesoblast being continuous longi- 

 tudinally throughout the trunk ; no trace of maxillular segment was 

 seen. 



* Proc. Roy. Phys. Soc. Edinburgh, xx. (1916) pp. 23-61 (1 pi.). 

 t Rend. Accad. Lincei Roma, xxv. (1916) pp. 121-8 (2 figs.). 

 :;: The Embryology of the Honey-Bee. Princeton and London : (1916) 282 pp. 

 (6 pis. and 95 figs.). See also Journ. Zool. Research, i. (1916) pp. 38-9. 



