I2 INANITION AND MALNUTRITION 



It was found that the endosperm is not absolutely essential, since without it 

 the embryos develop, though at a retarded rate and with marked changes appear- 

 ing later. The roots are less branched; stems simpler; leaves fewer, simpler and 

 smaller; inflorescence precocious and less well developed, showing various 

 abnormalities; fruits often aborted; all parts dwarfed. Comparison of sections 

 with those of normal controls in Nigella, Papaver, Solarium, Torilis, and Zea 

 showed that the internal structure also is much simpler in plants deprived of 

 their endosperm. In the stem, the cells are fewer and simpler; the cortex 

 shows fewer layers; the tissues of the central cylinder are less differentiated, the 

 vascular bundles being relatively undeveloped; the pith is relatively large. 

 Similar modifications occur in the root and petiole. In the leaf the epidermis 

 appears nearly normal, but the other tissues show a reduction in the number and 

 size of their elements. The greater the dwarfing, the more pronounced are 

 these modifications. The modification in the growth of beans observed by 

 Hottes upon the removal of the cotyledons was mentioned previously. These 

 are most striking examples of the profound morphological changes resulting 

 from an early partial inanition in the higher plants. 



Etiolation 



It. has long been known that a green plant deprived of light undergoes a 

 series of striking changes, designated as " etiolation." These changes are 

 associated with, and at least partly dependent upon, the lack of carbohydrate 

 food normally produced through the chlorophyll. The plant is thus thrown 

 upon its stored food material for nutrition, much like an animal during starva- 

 tion. In producing etiolation, Sachs ('87) believed that this interference with 

 nutrition is the primary factor. MacDougal ('03) while recognizing this factor, 

 was inclined to lay greater emphasis upon other factors, such as the withdrawal 

 of the direct effect of sunlight upon the living organism. Palladin ('18) similarly 

 considered etiolation as due only partly to deficiency of the organic assimilation 

 products, partly to lack of direct effects of sunlight, and partly to results of 

 diminished transpiration, with disturbance of the water balance. 



While the relative importance of the carbohydrate inanition factor in pro- 

 ducing etiolation is thus somewhat uncertain, the changes in the plant as a result 

 of etiolation are very marked. In addition to the yellow leaves and white stems 

 (green chlorophyll lacking in the absence of sunlight), von Sachs ('87) noted 

 that phanerogam seedlings develop longer shoot-axes and smaller leaves; and 

 that after a variable length of time growth ceases and death results in the mal- 

 formed, diseased plant. Further details in the process have been added by later 

 investigators, notably MacDougal ('03), who made extensive observations 

 upon the effects of etiolation in a large number of plants. He found that the 

 form and structure of the plant are usually much altered, but the results are 

 widely divergent in various types. There is an abnormal differentiation of 

 tissues, " some being suppressed, others accentuated and in some instances new 

 tissues arising. Variations occur in the form, size and number of the elements, 

 the structure and characteristics of the walls being materially different from the 



