91 



is accompanied by approximate!}' one four-hundredth part of the heat 

 which is ordinarily associated with the radiation of flames of the luminous 

 quality of those experimented with. Thus lISTature produces this cheap- 

 est light at about one four-hundredth part of the cost of the energy 

 which is expended in the candle-flame, and at but an insignificant 

 fraction of the cost of the electric light which is the most economic light 

 which has yet been devised. " Finally,'' the author concludes, ^' there 

 seems to be no reason why we are forbidden to hope that we may yet 

 discover a method (since such a one certainly exists and is in use on a 

 small scale) of obtaining an enormously greater result than we now do 

 from our present ordinary means for producing light." 



Dr. Curtice on the Animal Parasites of Sheep.— This Department has re- 

 cently issued a valuable Treatise on the Animal Parasites of Sheep by 

 Dr. Cooper Curtice, of the Bureau of Animal Industry. The work is 

 interesting from an entomological stand-point from the careful studies 

 which it contains of the following insects, of which the first-named is 

 perhaps the most important of all the ovine parasites : The Sheep Gad- 

 fly {CEstrus oris Linn.) ; the Sheep Tick of Louse-fly {Melophagus ovinus 

 Linn.); the Sheep Louse ( Trichodectes sphcerocephalus Nitzsch.); Goat-lice 

 ( Trichodectes limbatus Gervais and T. climax Nitzsch.). Though not true 

 insects, the Acari or Itch or Scab Insects or Mites, of which three spe- 

 cies are treated, may also be considered as belonging to the domain of 

 the entomologist. The species parasitic on sheep are Sarcoptes scabiei 

 DeG. var. oris, which causes the scab of the head ; Psoroptes communis 

 Furst. var. or/s, which causes the common scab ; and Chorioptes com- 

 munis \erh. var. ovis^ which causes the foot-scab. 



Some forty-four pages and eight plates are devoted to the parasites 

 named. The illustrations are excellent and very accurate, and repre- 

 sent, as far as possible, the life-history of the species. The three plates 

 devoted to (E. bovis are especially interesting and particularly Plates 

 II and III which represent sections of the head of a sheep with the Gad- 

 fly iarvse in situ in the sinuses and cavities. Through the courtesy of 

 Dr. Curtice we had the opportunity of examining the specimens from 

 which these latter phites were drawn and can vouch for their accuracy. 

 Plate I, however, is more or less inaccurate in its delineation of the 

 adult of (Estrusovis. 



The work deals at length, also, with the various intestinal and lung 

 parasites of the sheep and will be of great practical value both to the 

 sheep raisers and to veterinarians. 



Notes on Plant Lice.— Bulletin, Technical Series, Vol. I, No. 2, Article 

 Y, of the Ohio Agricultural Experiment Station contains the fourth 

 of Dr. Clarence M. Weed's papers entitled '• Contributions to a Knowl- 

 edge of the Life-history of certain Little-known Plant-lice {Aphididce),^^ 



