524 BOTANICAL GAZETTE [December 



LITERATURE CITED 



1. Czapek, F., Zur Lehre der Wurzelausscheidungen. Jahrb. Wiss. Bot. 

 29:321-390. 1896. 



2. Detmer, W., Practical plant physiology. Eng. trans, by S. A. Moor. 

 p. 508. London. 1898. 



3. Gager, C. Stuart, Tuber-formation in Solanum tuberosum in daylight. 

 Torreya 6:181-186. 1906. 



4. , Further note on the formation of aerial tubers in Solanum. Tor- 

 reya 6:211-212. 1906. 



5. Olufsen, L., Untersuchungen iiber Wundperidermbildung an Kartoffel- 

 knollen. Bot. Cent. Beih. 15:267-308. 1903. 



6. Peirce, G. J., Das Eindringen von Wurzeln in lebendige Gewebe. Bot. 

 Zeit. 52:169-176. 1894. 



7. Pfeffer, W., Druck- und Arbeitleistung durch wachsende Pflanzen. 

 Abhand. Konigl. Sachs. Gesells. Wiss. 20 3 : 235-474. 1893. 



8. Pond, R. H., Emergence of lateral roots. Bot. Gaz. 46:410-421. 1908. 



9. Reinke, J., Untersuchungen iiber Wachsthumgesichte und Morphologie 

 der Phanerogam-Wurzel. Hanstein's Bot. Abhand. Gebiet Morphol. und 

 Physiol. 13:1-38. 1 87 1. 



10. Van Tieghem, P., and Douliot, H., Recherches comparatives sur l'origine 

 des membres endogenes dans les plantes vasculaires. Ann. Sci. Nat. 

 Bot. VII. 8:1-660. pis. 1-40. 1888. 



11. Van Tieghem, P., Traite de botanique. Deuxieme edition, pp. 709-711. 

 Paris. 1 89 1. 



12. Von Hone, H., Uber das Hervorbrechen endogener Organe aus dem 

 Mutterorgane. Flora 63:227-234, 243-257, 268-274. 1880. 



EXPLANATION OF PLATE XXXVI 



Solanum tuberosum 



Fig. 1. — Outline of a longitudinal section of an ingrown sprout: A and B, 

 cellular structure at the regions marked A and B in the outline, showing well 

 developed columnar epithelium. — Zeiss oc. 4; obj. D. 



Fig. 2. — Longitudinal section through the tip of an ingrown sprout, with 

 adjacent tissue of the seed tuber, showing mechanical compression of the cells 

 of the tuber by the growing sprout and absence of any evidence of corrosion of 

 either cell walls or starch grains; the breaks in the cell walls are artifacts; 

 many of the starch grains have fallen out of the section. — Cf . figs. 3 and 4. 

 Zeiss oc. 4; obj. AA., lower lens only. 



Fig. 3.— Early stage in the development of a root within an ingrown 

 sprout; this section was taken at the area marked C in fig. 1; note the com- 

 pression of the cortical cells by the advancing root.— Cf. figs. 2 and 4. — Zeiss 

 oc. 4; obj. AA. 



Fig. 4. — Cross-section through a seed tuber, showing compression of the 

 wall cells of a channel made by an ingrown sprout. — Cf. figs. 2 and 3. — Zeiss 

 oc. 4; obj. AA. 



