32 



SCIENCE 



[N. 8. Vol. XL. No. 1018 



The meteorological service of India is begin- 

 ning aerological work witli balloons sondes. 



An extreme minimum temperature of 



— 91.9° 0. was recorded with a ballon sonde 

 on November 5, 1913, over Batavia, JaTa. 

 Anotber ballon sonde brougbt down a record of 



— 90.9° at 17 km. altitude on December 4. 

 Above tbis tbe temperature rose to — 57.1° at 

 26 km.8 



Pyrheliometric observations obtained from 

 ballons sondes in California last summer at 

 altitudes of 10 to 13 km. indicate a lower 

 solar constant of radiation tban is obtained 

 from observations at tbe eartb's surface after 

 transmission corrections bave been added. 

 Although a maximum altitude of 33 km. was 

 reached, no observations were secured above 

 13 fcm. because of the freezing of the mercury.'^ 



The unpublished papers of the International 

 Meteorological Congress held at Chicago in 

 1893 are now appearing "in tbe Monthly 

 Weather Beview. 



A CONFERENCE of observers and students of 

 meteorology and allied subjects will be held 

 in Edinburgh, September 8 to 12, 1914^ 



Charles F. Brooks 



Hakvaed Univeesitt, 

 May 18, 1914 



SPECIAL ABTICLES 



A CULTURE MEDIUM FOR THE TISSUES OF 

 AMPHIBIANS 



In the course of some experiments on the 

 culture in vitro of tissues from various amphi- 

 bians, considerable difficulty was encountered 

 in using blood plasma as a culture medium on 

 account of its very rapid coagulation. When 

 working with the tissues of the frog or of tad- 

 poles it was more convenient to use lymph 

 taken directly from some of tbe subcutaneous 

 lymph spaces. Preparations in lymph may 

 frequently be made before coagulation occurs, 

 but the lymph tends to become too watery for 



6 Nature, March 5, 1914, pp. 5-6. 

 ' C. G. Abbot, Scientific American, April 4, 1914, 

 p. 278. 



8 See Nature, February 12, 1914, p. 667. 



use a short time after the frog is killed, so 

 that only a small quantity is available from 

 any one animal. In most urodeles the scarcity 

 of available lymph prohibits its employment, 

 so that plasma was at first depended on almost 

 entirely for a culture medium. 



There is little outwandering or outgrowth 

 from the tissues of either the embryos or the 

 adults of amphibians unless the surrounding 

 medium is of more or less solid consistency. 

 Amphibian tissue will live for weeks in blood 

 serum or even in Einger's solution, but the 

 cells do not often grow or wander away from 

 the rest of the mass unless they come into 

 contact with a substance that evokes a thigmo- 

 tactic response. In searching for a convenient 

 substitute for blood plasma the endeavor was 

 therefore made to find a medium which would 

 remain fluid while being used, but which 

 would solidify to about the consistency of 

 blood clot afterwards. After some experimen- 

 tation it was found that a mixture of equal 

 parts of blood serum and a two per cent, solu- 

 tion of Griibler's nutrient gelatine afforded 

 a substitute that was very successful. 



Tbe preparation of the mixture is easy. 

 Blood drawn from the heart is stirred with a 

 fine glass rod and the coagulum removed. 

 The blood is then centrifuged to remove the 

 corpuscles, and the clear serum mixed with an 

 equal quantity of a two per cent, solution of 

 gelatine. The gelatine solution is previously 

 boiled and precautions are taken to prevent 

 contamination of any of tbe ingredients of 

 the medium with bacteria. I have used the 

 mixture after it had been kept for several 

 days, and found it to be practically as good a 

 culture medium as when perfectly fresh. 



The mixture becomes fluid when warmed 

 slightly and remains fluid for an hour or more 

 after being cooled to ordinary room tempera- 

 ture. I commonly keep it in small tubes of 

 glass, and by rubbing tbe tubes briskly with 

 the fingers sufficient heat may be generated to 

 cause the gelatine to liquify. Should the 

 supply of culture medium solidify while one 

 is putting up preparations, it is only neces- 

 sary to warm it slightly to keep it fluid for ad 

 hour or more longer. 



