The Structure of the Chloroplast considered in 
Relation to its Function. 
BY 
J. H. PRIESTLEY, B.Sc., 
Lecturer in Botany , 
AND 
ANNIE A. IRVING, 
Botanical Department , University College , Bristol. 
With two Figures in the Text. 
WING to its important role in photosynthesis, the structure of the 
vy chloroplast has received considerable attention from botanists, and 
it is interesting to note that a survey of the work done in this direction 
discloses important points of difference between the various observations 
made from time to time upon the structure of the chloroplast. 
It is clear, however, that the explanation given of the physiological 
mechanism involved must agree with the results of such structural in- 
vestigation. Considerations of this kind have led to the publication of the 
present paper. 
Historical. 
Pringsheim , 1 after placing green tissues in water at a temperature of 
5o°-6o° C. for 15-60 minutes, or after exposing them to steam for some 
time, examined the structure of the chloroplasts microscopically, and came 
to the conclusion that the ground-substance of the chloroplast is in the 
form of a hollow sponge-ball, the green colouring matter occurring in the 
meshes. Having heated the tissues in this manner, he noticed that 
a colouring matter, which he called hypochlorin, exuded in the form of 
variously coloured drops. 
Kerner 2 stated that the chlorophyll granules exhibited a pellicle-like 
thickened outer layer, within which was a colourless porous mass built 
up of reticular or scaffold-like threads. 
1 Pringsheim, Jahrbiicher wissensch. Botan., Bd. xii, 18S1. 
2 Kerner, Natural History of Plants, p. 371. 
[Annals of Botany, Vol. XXI. No. LXXXXII. July, 1907.] 
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