12 



SELECTION IN CLADOCERA ON THE BASIS OF 



the number of young in the first brood and the date of occurrence 

 of the second brood from the No. 1 mother were recorded. The 

 transfer of young to the next descendent generation was noted for 

 the appropriate mother, as was also the later discarding of the bottles 

 and the preservation of individuals from the No. 1 bottle. The 

 record of transfers made was given on the mother's as well as the 

 daughter's sheet. This double checking served as a safeguard in 

 case of any deficiency or discrepancy in the notes. Similar, but less 

 complete, records were made for the No. 2 and prime bottles. 



The data obtained in conducting the light tests for determining 

 the individuals to be selected was recorded in a separate note-book. 

 Any discrepancy as to the number in a given brood, its pedigree 

 designation, date of birth, etc., could again be checked by reference 

 to this book, so that in reality a three-entry system of note-keeping 

 was utilized. Very few discrepancies or deficiencies in the notes 

 have been found, and these were readily cleared up.^ 



A sample sheet of the loose-leaf notes is appended, and also a 

 page of the experimental-room notes. 



^ However, for the sake of complete safety, it was considered wise to keep up the three- 

 entry method of keeping notes. It did not prove unduly laborious. In any case, a new sheet 

 must be made for each set of three new bottles of the new generation, and naturally the notea 

 on the light tests required the entry of several of the items placed in the experimental note-book. 



