July i-sept. 30, 1918 Illustrations xm 
Contribution to the Knowledge; op Toxoptera graminum in the; Page 
South 
Fig. 1. Graph showing comparative number of young of the individuals of 
Toxoptera graminum in the A series plotted against the date of birth 
of the individuals... 98 
2. Graph showing the comparative number of young of the individuals of 
Toxoptera graminum in the B series plotted against the date of birth 
of the individuals__;. 99 
3. Graph showing comparative number of young of the individuals of 
Toxoptera graminum in the C series plotted against the date of birth 
of the individuals'. 99 
4. Graph showing comparative length of life of individuals of Toxoptera 
graminum in the A series plotted against the date of birth of the 
individuals. 100 
5. Graph showing comparative length of life of the individuals of Toxop¬ 
tera graminum in the B series plotted against the date of birth of the 
individuals. xoi 
6. Graph showing comparative length of life of individuals of Toxoptera 
graminum in the C series plotted against the date of birth of the indi¬ 
viduals. I0I 
7. Graph showing effects of temperature upon length of immature period 
. of Toxoptera graminum , plotted against the mean date of the imma¬ 
ture period. IQ g 
8. Same as figure 7, but in this diagram the average length of the imma¬ 
ture period of Toxoptera graminum is plotted against the average 
temperature for that period. 1Q g 
A Comparative Study op Salt Requirements for Young and Mature 
Buckwheat Plants in Solution Cultures 
Fig. i. Diagrams showing relative yields of buckwheat tops... .... 
2. Diagrams showing relative yields of buckwheat roots.. 166 
3. Diagram showing relative yields of buckwheat seeds. 169 
A Hitherto-Unreported Disease op Okra 
Fig. 1. Ascochyta abelmoschi: A section through a pycnidium on the host show¬ 
ing the outer and walls, the sporophores, and pycnsopores. 209 
2. Ascochyta abelmoschi: A portion of the pycnidium shown in figure 1... 209 
3. Ascochyta abelmoschi: A number of pycnospores, some of which are sep- 
tated, showing the variations in shape and size.. 210 
Anatomy op the Potato Plant, with Special Reference to the Ontogeny 
op the Vascular System 
Fig. 1. Solanum tuberosum: Diagram showing the course of the vascular bun¬ 
dles in the stem and the mode of origin of the vascular supply of the 
leaves (longitudinal). 226 
2. Solanum tuberosum: Diagrams illustrating the origin and course of the 
vascular supply of the flower. 235 
3. Solanum tuberosum: Diagram illustrating the mode or origin, orienta¬ 
tion, and development of the vascular tissue of the stem... 238 
4. Solanum tuberosum: Diagrammatic drawings of a series of sections 
through hypocotyl showing the position of the primary xylem and 
phloem groups, the changes from exarch to endarch, and the behavior 
of the phloem. 246 
