178 SCIENCE PROGRESS 



such methods as could be worked efficiently and safely under the limitations of a 

 Punjab village community. Since these limitations exclude expensive appliances 

 and dangerous toxic substances he was led to experiment on the use of carbon 

 dioxide. The effect of the C0 2 on germination was studied, and also the moisture 

 content of the wheat as found on the market, but the problems obviously needed 

 the collaboration of a biologist for adequate solution ; this was provided by the 

 appointment of the junior author, and the biochemical combination led to some 

 interesting results, of a type which is comparatively rare in entomological work, 

 though sufficiently familiar to plant physiologists. 



The detailed life-history of each of the principal insects infesting wheat in the 

 Punjab was worked out, and is presented with coloured plates. Their distribution 

 in relation to climate within the Punjab was also studied. The chief culprits 

 were the Dermestid Attagenus undulatus, Rhizopertha dominica, and the weevil 

 Calandra oryzce. 



The studies of germination, of moisture content, and of the effects of C0 2 and 

 S0 2 during germination, both with and without fresh air-supply, provided a large 

 amount of data, though the inclusion of a plant physiologist in the partnership 

 would have enhanced their value by preventing a few crudities in the interpre- 

 tation. Also, an exposure of wheat grains to chloroform vapour for a quarter of 

 an hour can scarcely be depended upon for sterilising purposes. The experiments 

 showed that the moisture content of ordinary Punjab wheat was usually low enough 

 to protect it against C. oryzcz, as Lefroy had stated, but that this dryness was no 

 bar to the activities of the two other pests, which are the more important except 

 in the damper parts of the province. The injury caused by C0 2 and S0 2 was 

 shown to be such as to preclude all possibility of using these gases as fumigants 

 for seed wheat. 



The next two chapters deal with the behaviour of the pests themselves in 

 atmospheres of C0 2 , nitrogen, and hydrogen. Extensive gas analysis experiments 

 are described, and a lengthy historical account of the physiology of respiration in 

 general is given. An " oxidase," or mixture of oxidising enzymes, was obtained 

 from the crushed larvae, and is considered to be the active agent in that output 

 of COj from the living larvaa which takes place under anaerobic conditions. The 

 effect of a rise of temperature in shortening the lethal period was demonstrated, 

 but without tracing any exact relation. 



Perhaps the most striking feature of the enquiry is the very pretty demonstra- 

 tion of specific differences between the three pests in their relation to moisture 

 (Chap. V.). Though the results themselves need explanation . . . indeed, they 

 open up a whole field of research . . . yet they in themselves explain all the known 

 facts of the distribution and activities of these pests in the Punjab. The insects 

 were starved at various temperatures in dry air and in saturated air. In the case 

 of R. dominica the change of humidity had practically no effect on the duration of 

 life ; in that of A. undulatus (the "woolly-bear" Dermestid) life was shorter at all 

 temperatures in moist air than in dry, while although for C. oryzcs the differences 

 were trivial at 40 C, yet the insects kept in moist air at 31 C. lived thrice as long 

 as those deprived of water. The run of the data seems to indicate further 

 interesting possibilities with regard to the death-point. 



The authors, having found naphthalene useless for food-wheat, on account of 

 the flavour which it imparts subsequently to the bread, finally devised an air-blast 

 method for cleaning out the damaged grains. 



The memoir covers so much ground that it cannot be exhaustive, but the 

 results are full of suggestiveness and of data which can be utilised in several 





