322 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



greater solubility of the substance of the nucleolus than of 

 the substance of the nucleus and cytoplasm would make it 

 the first to disappear under the attack of a parasite. 



In ficr. 14 h two characters of the cells are especially 

 noticeable: the nuclei are becoming disorganized, cavities 

 taking the place of the nuclear substance; and the cyto- 

 plasm is no longer so dense as in the younger cells shown 

 in fig. 14 a, nor does it stain so deeply with the orange G. 

 The degeneration of the nucleus is especially marked in 

 the cells c, z, h. These cells have lost their nuclei, except 

 the last traces of acromatic substance, before they have 

 themselves grown to their full size. 



The two upper cells of fig. 14 c have reached the maxi- 

 mum size of infected cells. It is impossible to say whether 

 they have grown to this size after their nuclei were reduced 

 to the condition depicted or while their nuclei were being 

 destroyed. I cannot say whether the smaller cells c, i, h 

 of fig. 14 h would ever have grown to the size of the upper 

 two in fig. 14 5, but the unusual growth of infected cells is 

 due to the bacteria, and it is the bacteria which also destroy 

 the nucleus or cause it to be destroyed. In the upper cells 

 of fig. 14 c the cytoplasm is no longer the clear color pro- 

 duced by orange G. This brownish yellow color is dulled 

 by the purple of the now extremely numerous bacteria. 

 The smudgy appearance of the cytoplasm of the cells in 14 d 

 is due to the mixture of the purple stain of the bacteria and 

 the brownish yellow of the cytoplasm, an effect which is 

 very striking in the preparations. The cells of fig. 14 d 

 also show the greatly reduced nuclei and the large central 

 vacuoles. Fig. 8 represents a cell from near the center of 

 the tubercle shown in fig. 7. The cytoplasm is crowded 

 with bacteria, the central vacuole is very large, the nucleus 

 is reduced to an elongated lumpy mass as seen in section, 

 or to a thin lumpy plate in the entire cell. 



When infected cells contain any considerable number of 

 bacteria, they cease to be able to divide. Freshly infected 

 daughter-cells of the cambium layer do divide, as fig. 15 

 shows. One is inclined to say that the disturbing, if not 



