BIOLOGICAL LABORATORY AT NAPLES 



are the general life principles that study of the one 

 may point a practical moral for the other. 



Indeed, it constantly happens that the student of 

 biology, while gazing through his microscope, hits 

 upon discoveries that have the most far-removed im- 

 plications. Thus a. few years ago it was discovered 

 that when a cell is about to bisect itself and become 

 two cells, its nucleus undergoes a curious transforma- 

 tion. Within the nuclear substance little bodies are 

 developed, usually threadlike in form, which take 

 on a deep stain, and which the biologist calls chro- 

 mosomes. These chromosomes vary in number in 

 the cells of different animals, but the number is al- 

 ways the same for any given species of animal. If one 

 were to group animate beings in classes according to 

 this very fundamental quality of the cells he would 

 have some very curious relations established. Thus, 

 under the heading " creatures whose cells have twenty- 

 four chromosomes," one would find beings so different 

 as "the mouse, the salamander, the trout, and the 

 lily," while the sixteen-chromosome group would in- 

 troduce the very startling association of the ox, the 

 guinea-pig, the onion, and man himself. But what- 

 ever their number, the chromosomes are always ex- 

 actly bisected before the cell divides, one-half being 

 apportioned to each of the two cells resulting from 

 the division. 



Now the application is this: It was the study of 

 these odd nuclear structures and their peculiar ma- 

 nreuvrings that, in large measure, led Professor Weis- 

 mann to his well-known theory of heredity, according 

 to which the acquired traits of any being are not trans- 



