2 [NANITION AND MALNUTRITION 



numerous essential factors in plant nutriment. Lack of any one of these factors 

 water, calcium, potassium, magnesium, iron, phosphorus, sulphur, manganese, 

 nitrogen, carbohydrates and possibly vitamins— will cause stunting of growth 

 with variable, degenerative cell-changes. These are expressed by morphological 

 and physiological derangements, often resulting ultimately in the death of the 

 organism. The effects are apparently most severe in the case of phosphorus or 

 nitrogen deficiency. 



In addition to the deleterious effects more or less common to all these 

 partial deficiencies, there are in each case certain peculiarities due to the special 

 functions which each of the food-elements normally performs. These peculiari- 

 ties appear also to vary considerably in different classes of plants. 



Thus water deficiency (aqueous inanition) is usually expressed promptly by 

 characteristic changes in form and structure of plants, on account of its funda- 

 mental importance in morphogenesis and adult structure, as well as in transporta- 

 tion. Of the various salts, those of calcium, potassium and magnesium are 

 especially essential for chlorophyll production and starch formation. Phos- 

 phorus appears to be more concerned with the transformation than with the 

 origin of carbohydrates. Cellulose formation proceeds in the absence of 

 phosphorus, but is impossible without calcium. Mitosis may occur in the 

 absence of calcium or of magnesium, but not without potassium or phosphorus. 

 The process of inflorescence and the development of the sexual organs in general 

 appear to be unusually susceptible to the effects of malnutrition, and in some 

 cases (especially in fern prothallia) a deficiency of calcium or nitrogen may 

 influence sex by inhibiting the development of the female organs (archegonia) . 

 Numerous other instances of characteristic effects of the various types of partial 

 inanition in plants will be cited in the following pages. 



Some of these effects of inanition upon plants, especially with reference to 

 cellulose, chlorophyll and starch production, are peculiar to the plant kingdom. 

 Most of the effects, however, resemble those found in animals. A study of these 

 effects is therefore of interest to the biologist, since the phenomena common to 

 plants and animals indicate characters of fundamental importance. A knowl- 

 edge of these fundamental characters is likewise useful in the analysis of 

 conditions found in the higher animals, and is essential to the comprehension 

 of many of the complex problems of human medicine, as will appear in later 

 chapters. 



The effects of inanition on plants will be considered in detail under (A) total 

 inanition (or on water only), and (B) partial inanition. Although subsistence on 

 water alone is, according to definition, a form of partial inanition, the results 

 are similar to those of total inanition, and are grouped with them for convenience. 



(A) Effects of Total Inanition, or on Water Only 



According to Winkler ('13), the theory has recently been emphasized (by v. 

 Gobel, Klebs and Sachs) that the morphogenesis of plants depends chiefly upon 

 t heir metabolic activities, in which case the production of abnormal forms through 

 inanition is to be expected. Palladin ('18) concluded that "each external condi- 



