800 



SCIENCE 



[N. S. Vol. XXXVI. No. 936 



feet or higher, the mountain hemlock is most 

 efficient, for not only is its foliage dense, but 

 its tapering spire-like crown offers but little 

 resistance to falling snow. 



In the light of the above facts forests may 

 be too dense as well as too thin for the maxi- 

 mum conservation of snow. The ideal forest 

 seems to be one filled with glades whose area 

 bears such proportion to the height of the 

 trees that the wind and the sun can not reach 

 the bottom. These glades can be produced by 

 the forester by judicious pruning and cutting 

 as well as by proper planting. However, the 

 mountain hemlock requires little or no prun- 

 ing to attain its maximum efficiency. 



In the field of hydrology, surveys of snow 

 on the Mount Rose and Lake Tahoe water- 

 sheds have been made since the beginning of 

 1910 to indicate to ranchers and power com- 

 panies in the basin below the amount of water 

 to expect during the season, and thereby to as- 

 sure the better control of the reservoirs. This 

 work will be extended to include a study of the 

 behavior of snow on typical slopes during ris- 

 ing temperature and wind with the view of 

 forecasting the probability and extent of 

 floods. For the purpose of offering foresters 

 in the national forests and others the ad- 

 vantage of the investigations in snow a course 

 is now planned at the University of Nevada on 

 the relation of mountains and forests to the 

 conservation of snow, including the improve- 

 ment of the storage of snow by the planting 

 and pruning of forests to assure the control of 

 stream flow and the increase of irrigation and 

 power resources. Other courses in general 

 meteorology have already been provided. 



The staff of the observatory consists of Pro- 

 fessor S. P. Pergusson, formerly first assistant 

 at Blue Hill Observatory, who is associate 

 meteorologist, Mr. Arthur L. Smith, observer 

 in Lake Tahoe Basin, and the writer, who is 

 in charge. 



Besides annual reports and news bulletins, 

 the more important recent publications are 

 Experiment Station Bulletin No. 79, "The 

 Avoidance and Prevention of Frost in the 

 Fruit Belts of Nevada," and an article on the 

 " Conservation of Snow : Its Dependence on 



Forests and Mountains," in Scientific Ameri- 

 can Supplement, Vol. LXXIV, No. 1914 (Sep- 

 tember 7, 1912), pp. 152-55. A bulletin con- 

 taining an elaborate presentation of the rela- 

 tion of mountains and forests to the conserva- 

 tion of snow is now being prepared. 



J. E. Church, Jr. 

 Eeno, Nevada 



SPECIAL ABTICLES 



THE CULTIVATION OF AN ECTOPARASITIC NEMATODE 

 OF A GUINEA-PIG ON BACTERIOLOGIC MEDIA' 



On May 6, 1912, while examining a guinea- 

 pig which had died of an unknown cause, it 

 was noted that the skin around and just an- 

 terior to the external genitalia was excoriated 

 and covered by a yellowish, cheesy exudate. 

 On examining the exudate under the low 

 power, a large number of actively motile em- 

 bryonic and adult nematodes were found. On 

 May 7 a second guinea-pig exhibiting a sim- 

 ilar, but less extensive, lesion and harboring 

 the same ectoparasitic nematodes was discov- 

 ered. Lately, a third guinea-pig was encoun- 

 tered, harboring the same nematode not only 

 around the external genitalia, but also on the 

 normal skin of the abdomen and thorax. Care- 

 ful examination of these and of a number of 

 other guinea-pigs has failed to reveal the pres- 

 ence of the nematode in the gastro-intestinal 

 tract or in any of the internal organs. 



A little of the caseous material from the 

 first two guinea-pigs was inoculated onto 

 moist earth and slants of Musgrave's amceba 

 agar and kept at room temperature (about 

 24° C). In a few days, a large number of 

 actively motile nematodes were found in these 

 cultures. The amceba agar cultures have, 

 since then, been carried through five sub- 

 cultures and the worms have also been suc- 

 cessfully carried through several subcultures 

 on slants of plain agar and ascites agar. The 

 plain agar and the amceba agar have proved 

 to be the best media, because the accompany- 

 ing bacterial growth is relatively limited in 

 amount. In several of the above subcultures 



^ A preliminary note, from tlie laboratory of 

 the Cmciimati Hospital. 



