91 



is accompauied by approximately oue foui-buudredtli part of the heat 

 which isordiuarily associated with the radiation of flames of the Umiinous 

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

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

 which is expended in the candle flame, and at but au 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.— Tllis 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 standpoint 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 ovisltinn.) ; the Sheep Tick or Louse fly {Melophagus ovhius 

 Linn.); the Sheep Louse ( Trichodectes sphwrocephalus Nitzscli.); 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. ovis, whicb causes the scab of the head ; Psoroptes communis 

 Flirst. var. avis, 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. bonis are especially interesting and particularly Plates 

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

 fly larvae 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 plates were drawn and can vouch for their accuracy. 

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

 adult of (Estrus ovis. 



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, Techuical Series, Vol. I, No. 2, Article 

 V, 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 [Aphididw),''^ 



