558 



SCIENCE 



[N. S. Vol. LIII. No. 1381 



cultivation make this method of obtaining 

 proper food for Cladocera perhaps less useful 

 in some cases than the one now to be de- 

 scribed. 



It seemed desirable to have a culture me- 

 dium which could be readily obtained any- 

 where and at any season of the year. Such 

 a medium has been obtained as follows: two 

 pounds of fine garden soil are placed in a large 

 battery jar (9 in. diameter) ; to this are added 

 six ounces of finely divided fresh (8 to 15 

 days old) horse manure and the whole is cov- 

 ered with 10 quarts of strained pond water. 

 Pond water is specified because Cladocera are 

 extremely susceptible to the toxic effects of 

 the salts of the heavy metals. Tap water 

 should be used with caution until proved in- 

 nocuous. The mixture is allowed to stand at 

 15° to 20° C. without disturbance for three 

 days when it is strained through silk bolting- 

 cloth. The proper straining is facilitated by 

 carefully dipping out and straining most of 

 the supernatant liquid and then agitating the 

 remainder and with it rubbing a very small 

 portion of the soil through the straining cloth. 

 The solution is then ready for use, though 

 in addition to being thoroughly stirred before 

 being placed in the culture bottles it is usually 

 diluted by adding pond water in the propor- 

 tions of from 1 to 4 to 1 to 2, depending upon 

 the degree of density in the appearance of the 

 solution. 



This culture medium has proved extremely 

 useful to the writer and is now used exclu- 

 sively for all his Cladocera cultures. No re- 

 newal of the solution in a culture bottle is 

 ordinarily required during the life of an in- 

 dividual Cladoceran. 'Not every make-up of 

 food proves equally satisfactory but persons 

 unaccustomed to handling such culture water 

 quickly learn the proper handling and dilu- 

 tion and very soon obtain excellent results. 

 This soil-manure solution is equally practi- 

 cable for rearing copepods and some, at least, 

 of the rotifers. 



Bacteria constitute the principal food ele- 

 ment in this culture medium. While a certain 

 amount of uniformity is attainable in such a 

 culture medium, such mass cultures are quite 



variable and it is obvious that this can scarcely 

 be considered a " standard " food. It is prob- 

 able that the proper bacteria could be reared 

 on agar plates, definite quantities introduced 

 into the culture bottles at definite intervals 

 and a really standard food thus obtained. 



Aethur M. Banta 

 Station for Experimental Evolution 



THE NEBRASKA ACADEMY OF 

 SCIENCE 



The thirty-first meeting of the Nebraska 

 Academy of Science, held in Bessey Hall, 

 University of Nebraska, Lincoln, on April 1 

 and 2, was one of the most interesting in the 

 history of the organization. The attendance 

 was about one hundred, comprising many edu- 

 cational institutions of the state and one or 

 two from adjoining states. The program was 

 so full it was divided into three sections. A 

 very pleasant feature was the annual dinner 

 held in Ellen Smith Hall, followed by Presi- 

 dent Walker's address, and a general discus- 

 sion of the needs and interests of the Academy. 

 Dr. Walker made a number of recommenda- 

 tions and suggestions for the advancement of 

 the organization, which has suffered in the 

 past from a lack of the interest and enthusi- 

 asm which usually mark the annual meetings. 

 The harvest time of the organization is be- 

 tween the annual meetings, if the officials are 

 sufficiently active and progressive. 



At the business session on Saturday morn- 

 ing a number of new members and the follow- 

 ing officials for the coming year were selected : 

 President, J. C. Jensen, Nebraska Wesleyan 

 University; Vice-president, H. O. Sutton, 

 Teachers' College, Kearney; Secretary, Rose 

 Clark, Teachers' College, Peru; and Treasurer, 

 P. K. Slaymaker, University of Nebraska. A 

 number of amendments to the constitution 

 were approved and the offer of Dr. Sheldon, 

 of temporary headquarters for the academy 

 with the Legislative Bureau, was accepted. 

 University Place was chosen for the 1922 

 meeting. 



W. F. HoYT, 

 Secretary 



