mack: dimensions of chromosomes. 125 



for this phyla are constant and equal to .83 /< and on page 12 

 states that "a study of the lengths of the ordinary chromosome 

 rod leads to the discovery that they constitute a series in arith- 

 metical progression the short chromosomes being consecutive 

 members." On page 25 he asserts that "the complexes of a 

 species and its variety appear to be identical; differences, if 

 existing, are too small to be recognized"; also that "the somatic 

 chromosomes are identical with those of the germ cells." He 

 further adds that "the total volume of ordinary chromosomes 

 is the same in the spermatogonial and primary spermatocyte 

 metaphases, whereas only half this amount appears in that of the 

 secondary spermatocyte." If the somatic chromosomes are iden- 

 tical with those of the germ cells we should naturally expect them 

 to follow his theory concerning the spermatogonial and the first 

 spermatocyte chromosomes in diameter, length, and volumes. 

 From a careful study of my results previously recorded it is very 

 evident that in no case was I able to find such a constant diameter 

 nor such a regularity in the variation in length of the chromosomes 

 in the material at hand. 



In order to ascertain whether this variation in size was peculiar 

 to the somatic cells only, I measured from seven to ten chromo- 

 somes in the metaphase in each of twenty-two cells of the first 

 spermatocyte in Gryllus domesticus, and those of one in the 

 anaphase, and those of two in the metaphase of the primary 

 spermatogonian, the lengths of the chromosomes in one of the 

 best cells of the spermatocyte were 3.5, 3.75, 2.5, 2.25, 2.25, 2.25, 



2, 2, 5, and 1.5,". The corresponding diameters were 1.25, 1.75, 

 1.5, 1.75, 1, 1, 1, 1, 1.25, and 1,". The lengths of another were 



3, 2.5, 2.25, 2.25, 2.25, 2, 2, 1.5, 1.5, and 1.25//, and the cor- 

 responding diameters were 1.25, 1.5, 1.5, 1.25, 1.25, 1.75, 1.5, 

 1.25, 1, and 1.25 ,". The lengths for one of the best spermatogonial 

 cells were 3, 2.5, 2.5, 2.5, 2.25, 2.25, 2, and 2,", while the di- 

 ameters were .50, .75, .75, .62, .75, .75, 1.25, and .50,". I could in 

 none of these cases, as can easily be seen, find an absolute constant 

 diameter as Meek mentions for the same animal in the same 

 species, although there were several diameters which were iden- 

 tical. Nor could I find the relation between the lengths which 

 could be called "an arithmetical series whose common difference 

 was less than half of the diameter." In order to avoid any error 

 which might occur, due to fixation, I was careful to choose cells 

 which were similarly located in the testis. 



