THE DIPLOID CHROMOSOME COMPLEXES OF THE PIG 165 



familiar with the characteristic shape of the first spermatocyte 

 chromosomes, as found in the grasshoppers, some of the bugs 

 and other forms, will recognize similar forms here. These forms 

 were not shown in the previous study of the spermatogenesis 

 of the pig (Wodsedalek, '13). 



THE SOMATIC CHROMOSOMES 



The present report must necessarily be preliminary in nature 

 and intended rather to point out certain conditions that exist, 

 than to offer a final solution of the problem. With this in 

 mind, two embryos were selected for the study of the chromo- 

 some conditions in the body — one embryo of eight, the other of 

 fifteen millimeters. The smaller embryo was fixed entire, while 

 the larger one was teased. The teasing was not sufficient to 

 interfere greatly with the recognition of the various tissues. The 

 fixation in both was excellent, as may be judged from the draw- 

 ings, and was fully as good as was obtained in the germ cells. 

 Only those cells were selected for drawing which were clearly un- 

 cut and in which the chromosomes were well separated and dis- 

 tinct. Small cells possessing a large number of chromosomes, 

 may, even in the most perfectly preserved material, occasion- 

 ally present one of two places where the number of chromo- 

 somes involved is uncertain. This will be spoken of later. 



The chromosome 7iumber 



It was soon found that the somatic chromosome number was 

 not constant. The variation ranged from forty to fifty-seven, 

 and one cell was found in w^hich at least seventy-four chromatin 

 bodies were counted. Ninety-one cells were counted. (See 

 page 167.) Drawings of the various types of cells found in the 

 embrj^o are given in figures 23 to 88. Although, at first, the 

 greatest variation was thought to be confined to the blood, as 

 more tissues were studied, it was found that the blood was not an 

 exception to the rule and that a similar range of numbers was 

 "present in each tissue in which a number of active cells were 

 found. The following table gives in detail the distribution of 

 the variations in the thirteen tissues studied. 



