TRANSACTIONS OF SECTION K. 667 
portions of the disc give rise to upright branches. Tach cell contains a 
single parietal chloroplast, a nucleus and a pyrenoid. 
Reproduction is by means of megazoospores, microzoospores and 
isogametes. 
The plant is referred to the Chaetopeltidee section of the 
Chaetophoracee. 
A number of individuals were observed growing under similar con- 
ditions ; some of their cells liberated gametes which fused in pairs; the 
contents of other apparently homologous structures germinated within the 
wall of the mother cell to form filaments. 
In accordance with the work of Klebs the appearance of the various 
phases which occur in the life histories of many Algz has been accounted 
for by definite changes in the environment. 
In Trichodiscus elegans such an explanation seems insufficient since 
different forms of reproduction take place under identical conditions. 
7. The New Industry of Rubber Cultivation. By J. Parkin, M.A. 
FRIDAY, AUGUST 27. 
The following Papers were read :— 
1. The Chemistry of Chlorophyll. By Professor R. WiLustTarrer. 
The older chemical investigations of chlorophyll have dealt with 
decomposition products too far removed from the natural dyestuff for them 
to be of real assistance in determining the constitution of chlorophyll. Of 
permanent value, however, is a fact established by Hoppe-Seyler, and also 
by Schunck and Marchlewski—namely, that phylloporphyrin, a degra- 
dation product of chlorophyll, is closely related to derivatives of hemin. 
Deductions have been drawn from this fact as to the similarity of 
and close relationship between the pigments of blood and green leaves, 
but such are unwarranted. Far more important than the similarity of 
the degradation products is the difference between chlorophyll and 
heemin with regard to the metal bound up in a complex manner in their 
molecules. It is the nature of this metal which conditions the catalytic 
function of the pigment. The function of hemoglobin as a carrier of 
oxygen is to be attributed to its iron content; on the other hand, it is 
the magnesium in chlorophyll to which an important part in the assimila- 
tion of carbon dioxide must be ascribed. 
The author has established that the chlorophyll of all classes of plants 
from the Algse to the Dicotyledons contains magnesium and no other metal. 
This has been overlooked previously, possibly because the complex is very 
sensitive towards acids, which completely eliminate the metal. The 
metallic complex is far more stable towards alkalis. On heating with 
potassium hydroxide at 240° magnificent crystalline compounds are 
obtained which when ignited leave a residue of magnesium oxide amount- 
ing to 6 to 7$ per cent.: they are chemically carboxylic acids. The 
preparation of these well-defined crystalline compounds in a pure state 
from leaf extracts of various plants has served as a proof for the existence 
of magnesium in chlorophyll and for the nature of its incorporation in the 
molecule. 
The continued action of alkali yields first green chlorophyllins, which 
are tricarboxylic acids; then blue glaucophyllin and red rhodophyllin, 
which are dicarboxylic acids, and finally red pyrrophyllin and phyllo- 
