125 



Hutchinson (C. M.). Report of the Imperial Agricultural Bacterio- 

 logist.^ — Scientific Reports Agric. Research Institute, Pusa, for 1916- 

 17; Calcutta, 1917, pp. 103-118. [Received Uth January 1918.] 



Since a more complete knowledge of the life-history of Nosema 

 hombycis and of the reciprocal relationship between this parasite and 

 its host are necessary for the control of pebrine among silkworms, 

 experimental research on the points of hereditary infection and infec- 

 tion through contagion or ingestion of the parasite have been carried 

 out with the following results : — Infected eggs have been found to 

 produce silkworms that succeed in reaching the cocoon stage, provided 

 that sufficient space and suitable food are available. Such individuals, 

 however, cannot be used for breeding purposes as the resistance 

 acquired through suitable environment is only sufficient to hold in 

 check the multiplication and spread of the parasite. The principal, 

 if not the only means of infection, other than by hereditary trans- 

 mission, has been proved to be by ingestion of the parasite spores with 

 the food, these being present in great numbers in the dust of rearing 

 houses. They also may be excreted by infected but still feeding 

 indi\aduals, which in this way infect the leaves of the food-plant. 

 Infection, once introduced, spreads rapidly through the dissemination 

 of the spores by human beings, insects and dust, not only in the same 

 house but also to neighbouring rearing houses. Cocoons and eggs 

 received from a distance, though hereditarily free from the disease, 

 may be contaminated during examination in an infected house, owing 

 to faulty technique, which results in the accumulation of infective 

 material in the building. Of the action of antiseptic insecticides in 

 rearing houses little at present is known, attention having been directed 

 towards the determination of the viability or persistence of infective 

 power of the pebrine spore under varying natural conditions. It has 

 been found that desiccation for six months did not destroy the 

 infective power of the spores, whereas they were rendered innocuous 

 in a month by moderate moisture at the same temperature. The 

 stimulus determining the generation of the spore is apparently the 

 combination of moisture and suitable temperature found in the gut 

 of the silkworm, and it is probable that the deleterious effects of 

 continued moisture upon the vitality of the non-ingested spore are due 

 to prematurely induced development, not carried so far as germination, 

 but resulting in either partial or total loss of vitality. Further 

 investigation is necessary regarding the effect of climate or manurial 

 treatment upon the nutritional value of the mulberry leaf, together 

 with the resulting reaction upon the resistance of the silkworm to 

 infection. 



AxsTEAD (R. D.). A Swarm of Insects. — Planters^ Chronicle, Bangalore, 

 xii, no. 47, 21th November 1917, p. 594. [Received 12th January 

 1918.] 



A remarkable swarm of insects is reported to have occurred last July 

 on'a coffee plantation situated on the leeward side of a hill, its effect 

 being similar to that of a cyclone, shade trees having their branches 

 bent and broken by the weight of the insects, while the coffee was 

 covered, though to a less degree. The insect has been identified as a 

 Pentatomid bug, Ochrophora montana, which however only did 



