166 



EGBERT T. HANCE 



Table of chromosome numbers in the various tissues studied 



The figures at the top of each column refer to the number of chromosomes 

 and the figures in the columns indicate the number of examples found 



Blood 



Brain 



Connective 



Amnion 



Myotome 



Heart 



Diaphragm 



Wolffian body 



Lung 



Umbilicus 



Limb buds 



Optic cup 



Liver 



Number of cases 



12 

 44 

 9 

 4 

 3 

 1 

 1 

 3 

 1 

 2 

 5 

 1 



91 



Text figure 1 illustrates graphically some of the conditions 

 given in the above table. On this chart no one type or group of 

 cells appears to be predominant. It seems very probable that 

 when a larger number of cells are studied, this curve will 

 'straighten' out, showing approximately the same number of cells 

 falling in the various classes. 



Had the variation in number been but one or two it might have 

 been attributed to errors in observation and drawing because of 

 the many chromosomes in the cells. But the numbers ranged 

 from forty to fifty-seven, which excludes the possibility of error 

 from this source. An error of one or two chromosomes might 

 well be made but, considering the excellence of the preparations 

 and the care taken in checking the drawings, not one of seven- 

 teen. In recording the chromosomes my constant effort was to 

 underestimate rather than to overestimate the number. It was 

 frequently difficult to determine whether the chromatin body un- 

 der examination was really single or composed of two parts. In 

 all such cases, except where I was finally able to determine defi- 



