380 The Physiology of Plants BOOKIII 



mode of incorporation of the new material into the living 

 substance, the most intricate of all the problems of nutri- 

 tion, must be postponed for the present. The second 

 includes the processes of temporary deposit of the trans- 

 located substances and their subsequent utilization. 



Such temporary deposits or stores have given rise to the 

 recognition of what are now known as reserve materials, 

 and their investigation has been one of the features of the 

 period under consideration. 



I. CARBOHYDRATES, (a) Starch. As already mentioned 

 in a previous chapter, the researches of Sachs in 1860-4 

 led to the recognition of starch as the ' first visible product 

 of assimilation '. It was observed by him, and by Naegeli 

 at about the same time, to occur as little specks in the 

 body of the chlorophyll corpuscle. The idea that these 

 grains are not necessarily the final stage of a constructive 

 process first appeared in the work of Boehm, published in 

 1874-6, in which he showed that sometimes such starch 

 owes its origin to a transference of some of the carbo- 

 hydrates of the seed back to the leaf, in the absence of 

 light and of carbon dioxide. More complete recognition, 

 indeed the first definite statement, of the fact that such 

 starch grains are truly reserve materials, was afforded by, 

 and was the consequence of, the researches of A. Meyer in 

 1885 and 1886. Still fuller information was derived from 

 the investigations of Brown and Morris in 1893, which left 

 no doubt upon the matter. 



Perhaps the most noteworthy researches on the deposi- 

 tion of starch made during the nineteenth century were 

 those of Schimper, published in 1880. His attention was 

 first given to the relations between the starch grain and 

 the chloroplastid to which, as we have seen, attention had 

 been drawn nearly twenty years earlier by Sachs. He soon 

 extended his inquiries into the conditions of the storage of 

 starch in other parts of plants, and was successful in ascer- 



