98 A SYSTEMATIC AND STRUCTURAL ACCOUNT OF AVRAINVILLEA. 



The protoplasm forms a rather thin parietal layer in most 

 cases. Tliis is the case in many of the filaments of A. ^japuana, 

 but towards their free ends the layer of protoplasm becomes thicker, 

 so that at the apex, and for a varying distance below it, the cavity 

 is completely filled by the protoplasm. In some filaments this mass 

 of protoplasm is like that in other parts (fig. 9), but in some it is 

 coloured deep reddish brown of varying opacity. When broken into 

 fragments, this substance has a somewhat resinous appearance, and 

 has not the roughly granular structure of the clearer apices. Owing 

 to the dark colour, the efiect of staining reagents cannot be properly 

 observed, but probably this substance is altered protoplasm con- 

 taining a colouring matter. This deeply-coloured mass sometimes 

 reaches the very apex of the filament ; in other cases it ends below 

 the apex with a more or less sharp outline, and is capped with 

 roughly granular protoplasm (fig. 10). 



The chlorophyll-grains are distributed through the protoplasm 

 very unequally. In some filaments they are crowded, while in 

 others they are very few. As a general rule, they are crowded near 

 the apex of a filament, and become gradually scarcer in passing 

 back from the apex. They are rounded, polygonal or irregular in 

 outline, and always possess a clear central pyrenoid. It is often 

 very difficult to detect the presence of the chlorophyll-grains in 

 parts where the protoplasm is very granular, and their green colour 

 is often rendered invisible by the presence of a yellowish or brownish 

 colouring matter throughout the protoplasm, but by examining the 

 clearer parts of the filaments the clear green colour of the chloro- 

 phyll-grains can be seen in all the species. In A. lacerata there is 

 scarcely any colouring matter in the protoplasm of most of the 

 filaments, and hence the chlorophyll-grains are very conspicuous. 

 The pyrenoid stains dusky purple with iodine very readily. 



The amount of starch present in the filaments varies considerably 

 in different specimens of the same species, and in different parts of 

 the same plant. In the younger parts of the filaments small starch- 

 grains are often seen in connection with the chlorophyll-grains, 

 either inside them or at the periphery. In the older parts of the 

 frond, and especially in the rhizoids, the starch-grains are often 

 very numerous, forming the chief part of the cell-contents, and 

 completely filling up some of the smaller rhizoids. In A. papuana 

 they are kidney-shaped, in A. cccspitosa spindle-shaped, in A. comosa 

 the same, or irregularly ovoid. 



The nuclei are irregularly distributed in the parietal layer of 

 protoplasm. They are usually considerably larger than the chloro- 

 phyll-grains, and much more granular. Of the staining reagents 

 that we employed, picric aniline blue was the most successful in 

 differentiating the nucleus. In fig. 11 some nuclei and chlorophyll- 

 grains are represented in a filament of A, papuana; the nuclei are 

 very large, and the chlorophyll-grains few. 



A yellow or brown colom'ing matter is present in dried or spirit 

 material of all the species. It is distributed through the proto- 

 plasmic layer, and gives the filaments different shades of colour, 

 from greenish yellow to orange and reddish brown. The very dark 



