OKLAHOMA ACADEMY OF SCIENCE 31 



advantage gained is expressed in the greater vigor of tlie larvae 

 rather than in earlier hatching. 



The effect of ammonium hydroxide in strength of .006% to 

 .009% was likew^ise accelerative. 



Potassium hydroxide causes acceleration ot the cleavage rate 

 only in stronger concentration than sodium hydroxide, .006% to 

 .017% being the range necessary. Neither barium hydroxide nor 

 chromium hydroxide were found to have accelerating effects. 



Thyroid extract was found slightly to increase the cleavage 

 rate, but the experiments were not satisfactory in this case, so a 

 more definite statement cannot now be made. 



Philocarpine hydrochlorate in weak solutions produced an 

 effect which was in proportion to the concentration within the 

 range of acceleration. 



It is suggested from these experiments that probably hydrox- 

 ides which are of elements belonging to the first group of the 

 periodic series, when used in extremely weak solutions have :be 

 property of accelerating cleavage, while those of other groups of 

 the series do not possess this power. 



The writer is of the opinion that all of the agencies which may 

 lie used to accelerate the division rate, produce their effects by 

 activating intracellular enzymes, the activity of which controls the 

 rate of progress of the mitotic processes. 



The data on the experiments reported here will be published in 

 the Biological Bulletin for July, 1922. 



XV. A THIRD CHRISTMAS BIRD CENSUS 



Margaret M. Nice. 



Norman, Oklahoma. 



The Christmas Bird Census in 1921 was the most successful 

 of the three we have taken here in Norman; in 1919 we saw 35 

 .species and over 1,000 individuals ; in 1920 ; 33 species and 800 in- 

 dividuals, while in 1921 we recorded 39 species and over 2,000 indi- 

 viduals. The larger number of species seen this winter was partly 

 due to the use of an automobile which gave us a wider range, but 

 even over the same route traversed in the previous years we saw 

 36 species, so that the extra trips in the car gave us only three 

 more species. 



The census was taken Dec. 26, from 8:20 a. m. to 12:20 p. ri.. 

 and 2 :00 p. m. to 4 :30 p. m. The weather was clear, the ground 

 1)are, the wind south and the temperature 28° at the start and 46° 

 at the return. We covered eight miles on foot and sixteen in die 

 automobile. 



