22 



SCIENCE 



[N. S. Vol. SLV. No. 1149 



eggs and difficult to see the larvas in themass 

 of fermenting banana ordinarily nsed in rear- 

 ing Drosophila. For this reason and for many 

 others one can clearly see what the advantages 

 of a transparent solid medium might be. 



Banana agar was made as follows : Five or 

 six bananas were mashed up in 500 c.c. of 

 water. This was allowed to infuse on ice over 

 night, after which the liquid was passed 

 through cheesecloth. Powdered agar-agar was 

 then added in the proportion of IJ grams to 

 100 c.c. of the banana infusion. This was then 

 heated until the agar had dissolved. The 

 liquid was next filtered through a thin layer 

 of absorbent cotton into test tubes. The tubes 

 were then plugged, sterilized and slanted in 

 the customary manner. 



Media so prepared are quite transparent. 

 Greater transparency may be obtained, of 

 course, by repeated filtration, but this removes 

 too much from the food value. The slanted 

 tubes give about 6-7 c.c. of food with a feed- 

 ing surface of about 15 sq. cm. 



Adult Drosophila are inserted into the tubes. 

 The tubes are then incubated at 35° C. or 

 kept in some other warm place. In a day or 

 two the small white eggs may be seen deposited 

 everywhere on the surface of the agar. In a 

 day or two more the eggs hatch and the small 

 larvse can be seen working in the medium. 

 The average number of days required to com- 

 plete the cycle on the agar from egg to adult is 

 about thirteen. This is three days longer than 

 the average number of days required on the 

 ordinary fermenting banana mash. This 

 means that the amount of available food is too 

 low. That this is the case is further shown 

 by the fact that some of the larvae die prior to 

 pupation, and that the flies are somewhat 

 undersized. It is highly probable that the 

 am.ount of food may be increased by the use of 

 some concentrated form of food like banana 

 flour. An increase of the feeding surface may 

 likewise help. 



We have also succeeded in rearing Droso- 

 phila on potato ascar. The average number of 

 days required to complete the life cycle is 15 

 on this medium. The flies are very much 



smaller than those reared on banana agar. 

 Clearly, the amount of available food in the 

 potato must be very small. 



Of course, bacteria always develop on the 

 medium and sometimes we are troubled by 

 molds. The bacterial growth does not seem 

 to harm the larvae and the molds are usually 

 destroyed by the larvse just as soon as they 

 hatch. Sometimes the fungus growth becomes 

 too luxuriant between egg deposition and 

 hatching. At such times the larvK are killed 

 by the growth, but this is exceptional. It is 

 well to take all bacteriological precautions in 

 handling the tubes. 



The agar method for rearing Drosophila 

 has the following advantages. The eggs 

 " stand out " clearly and hence the time of 

 deposition and hatching can be noted. The 

 larvse can also be clearly seen and their habits 

 observed. By using various synthetic solid 

 media, Drosophila may become the subject for 

 interesting nutritional experiments. Our 

 solid medium has the slight disadvantage that 

 the concentration of the food is too low. This 

 difficulty can probably be remedied by the 

 addition of some concentrated form of food 

 like banana flour. 



J. P. Baumberger, 

 E. W. Glaser 



BussEY Institution 



THE NEW YORK MEETING OF THE 



AMERICAN ASSOCIATION FOR THE 



ADVANCEMENT OF SCIENCE 



The sixty-ninth meeting of the American Asso- 

 ciation for the Advancement of Science and af- 

 filiated national scientific societies was held in 

 New York, December 26 to 30, under the presi- 

 dency of Dr. Charles E. A-'an Hise. 



Owing to the large nimiber of organizations 

 brought together at one time, and to the fact that 

 many local institutions are intimately related to 

 these organizations, the places of meeting were 

 widely scattered. The general headquarters of the 

 association were maintained in Earl Hall of Co- 

 lumbia University, and the various buildings of 

 the university served very admirably for the meet- 

 ings of many of the sections and affiliated so- 

 cieties. Others met at the American Museum of 

 Natural History, at the College of the City of New 



