The Process of Heredity 531 



The data of five other series, ahnost as complete as the one just 

 described in detail, are on hand and furnish many interesting 

 comparisons and some new facts. There was a surprising 

 uniformity of results in the three other series conducted at about 

 the same time as the type series. After the development of a 

 method the results of all experiments that were carefully performed 

 were as similar as could be expected. Some of the earlier series, 

 however, gave results that varied widely in some particulars from 

 the type described. The plan followed is to take up first the series 

 in w^hich all precautions were used, presenting any new or inter- 

 esting data as briefly as possible. Then will follow a very brief 

 statement of the results of earlier series in which no special effort 

 was made to equalize conditions of parent or embryos. Following 

 that will come a statement of confirmatory or contradictory results 

 of incomplete or partial series. 



2 Other Series 



Series 2, July 5, 190'/- This was more like the type series 

 than was any other complete series. The experiment was, how- 

 ever, conducted in a somewhat diff^erent manner. Fresh lots of 

 fish were used and after three hours twenty eggs that had success- 

 fully cleaved were selected from each of the four strains. No 

 careful counts of blastomeres were made but it was noted that there 

 was no distinct difference in time rate of cleavage between the 

 pure and hybrid strains. 



At 14 hours: Ocular micrometer measurements of blastodisc 

 diameters of all embryos, gave the following averages: H pure, 

 .88 mm.;// hybrid, .87 mm.; M hybrid, .91 mm.; M pure .89 mm. 

 The differences were too small to be significant and it is probable 

 that the influence of foreign sperm had not made itself felt to a 

 measurable extent as yet. 



At 19 hours: Average blastodisc diameters of all eggs: // pure, 

 1.27 mm.; H hybrid, 1.12 mm.; M hybrid, 1.08 mm.; M pure, 

 I.I I mm. Here the difference between the H hybrids and the H 

 pures was quite marked, but that between the two majalis strains 

 was still very shght. 



At 22 hours: Camera drawings of each of the embryos were 



