NOTES ON RECENT RESEARCH. 



1125 



Such a case in point occurred when the eastern emigrants, pushing 

 out west, planted Potatos in the home of the then unknown Colorado 

 beetle (afterwards only too well known as the "Potato bug"). This 

 beetle fed upon the wild Sand Burr (Solarium rostratum), a plant be- 

 longing to the same natural order of plants as the cultivated Potato, so 

 that when it found such a luxuriant growth of more suitable food, it 

 deserted its old host plant, and, multiplying in millions, spread through 

 the Potato-fields of the whole of the United States, and is still one of 

 their greatest pests. 



If every insect's parasite were as effective under all conditions as is 

 claimed by the one section, surely the "Potato bug," with its soft-bodied 

 larva?, would have been kept in check by its natural enemies. 



This is an admirable illustration of the case where the parasite, if any, 

 did not increase in proportion to its host. 



Many other instances might be quoted to show how insect pests in 

 their native land remain and become increasingly formidable enemies with 

 the spread of cultivation. The Chinch bug and the Hessian fly, 

 common in America, levy an incredible toll on the wheat-fields of the 

 States, and though the latter has a number of well-known parasites, and 

 the actual home of both pests is well known, they both have to be 

 combated with mechanical methods, sowing catch crops, or the doubtful 

 spreading of fungus germs. 



Reference is also made to the great increase in the scale insects, aphis 

 and grubs which attack the trees of our orchards, special note being 

 made of red scale, San Jose scale, black or brown olive scale, white 

 louse and mussel scale. In bringing a most interesting article on insect 

 life to a conclusion the writer points out that he is quite in unison 

 with other economic entomologists who have carefully studied the 

 question of the relative value of predatory or internal parasites from all 

 points, in agreeing that, while they do their part in acting as a check on 

 the spread of the countless millions of injurious insects, and minimising 

 the damage caused, it is only under exceptional circumstances, and in 

 isolated cases, that they have done more. Just as the noxious insects 

 appear in immense numbers one year, and not in the following one, so is 

 the supply of the parasites variable (even when known to exist) ; and 

 naturally, though they might do very good work one year, the next will 

 find them wanting. — H. G. C. 



Seeds and Temperature. 



Seeds, Resistance of, to High Temperatures. Note by Henry 

 H. Dixon, Trinity College, Dublin {Ann. Bot. vol. xvi., No. 64, p. 590). 

 Abstract of paper read before Section K of the British Association, 

 Belfast, 1902. — " Various experimenters have investigated the limits of 

 temperature which spores of the lower plants and animals can withstand. 

 The results they have obtained show that these spores, if dry, can ger- 

 minate after exposure to the lowest temperatures obtainable, while the 

 upper limit for similarly dried spores lies between 100° C. (212° F.) and 

 130° C. (266° F.). For seeds of the higher plants also, it has been more 

 recently shown that the lowest temperatures available are without harmful 



