6 PLANT PHYSIOLOGY 



5, 1. 43, for amides read amino-acids 



6, 11. 4-5, for while, on the other hand read and between these intercellular 

 spaces filled with air. The volume relations existing between the cell-cavities 

 and the intercellular spaces are very varied. In ordinary foliage leaves the 

 intercellular spaces amount to about a quarter to one-fifth of the entire volume ; 

 but that proportion is much exceeded in water plants. UNGER (1854) found 

 that about two-thirds of the volume of the leaf of Pistia consisted of inter- 

 cellular spaces, and only one-third of cell substance. The usual chemical 

 analysis of a plant tells us nothing of these intercellular spaces, and yet these 

 are of fundamental importance. All plants, however, are not so elaborately 

 constructed ; 



7, 11. 44-7, delete We may further . . . swollen body 



8, 11. 1-2, for (such as that . . . greatest value read was carried out by REINKE 

 and RODEWALD (1881-3), and the service they thus rendered was especially 

 valuable, inasmuch as they showed that such a sample by no means consisted 

 of proteid only. 



1. 15, for Amide bodies read Amino-acids 



9, 11. 18-52, for This organization . . . homogeneous solution read In order 

 to study this organization, protoplasm has been examined with the very 

 newest and strongest objectives. These investigations, however, have led to 

 no interpretation that has received universal acceptance. From the zoological- 

 anatomical point of view several theories have been advanced based on the 

 belief that protoplasm consisted of distinct fundamental units, granules, or 

 nbrillae, or reticula formed by their union, or, finally, of small alveoli (BiJTSCHLi, 

 1892). From the botanical standpoint, on the contrary, it has been held that 

 there is no constant and fixed structure in the protoplasm, but that, accord- 

 ing to circumstances, it may be reticular, fibrillar, or alveolar (BERTHOLD, 

 1886 ; KLEMM, 1895 ; FISCHER, 1899 ; DEGEN, 1905). On the whole, botanists 

 appear to lean more and more to the view held by BERTHOLD (1886), A. MEYER 

 (1895), and A. FISCHER (1899), namely, that protoplasm is a fluid (water) in 

 which a mixture of substances with large molecules, such as proteid, or even 

 more complex bodies still, are in part dissolved, in part in a state of suspen- 

 sion. When microscopically examined, this fluid often appears quite homo- 

 geneous, but the ultra-microscope (GAIDUKOW, 1906) demonstrates distinct 

 particles in it, as in colloidal solutions. Such colloidal solutions not infrequently 

 exhibit the characters of ' pseudo-solutions ', differentiating themselves into 

 a more fluid portion (i.e. water with solids in solution) and a more solid portion 

 (i.e. solids containing dissolved water). Indeed, according to circumstances, 

 the solids may assume the form of a honeycomb whose cavities contain fluid 

 substances, or may take on the form of granules, fibrillae, or reticula. In 

 protoplasm also, such a structure may be explained by pseudo-solution pheno- 

 mena ; formation and redissolution of these structures may continue to take 

 place during the life of the protoplasm (DEGEN, 1905). Similar structural 

 appearances, again, may arise on the death of the protoplasm. As FISCHER 

 (1899) has shown, the reagents employed in ' fixing ' act in a similar manner 

 on the proteids of the protoplasm, and one is able to demonstrate very different 

 structural features in the protoplasm according to the nature of the fixative 

 employed. 



Although, in spite of these investigations, the ultimate structure of the 

 protoplasm has not as yet been unveiled, still no one can any longer believe 

 that it is merely a homogeneous solution of the numerous substances found 

 in it. 



