352 Mottier. — On Certain Plastids , with Special Reference to 
From the foregoing it is clear to the writer that aleurone or protein 
granules in Zea arise from definite primordia not unlike the primordia of 
leucoplasts and chloroplasts as regards their morphological and micro- 
chemical properties. That is, they fix and stain like the primordia 
of leucoplasts and chloroplasts. 
Ricinus. 
The seed of Ricinus communis has been a favourite object for a study 
of the aleurone content of the cell. The earlier observers devoted their 
studies largely to the morphological structure and microchemical reaction 
of the mature granules, and the literature on the subject is somewhat 
extensive. It is not the writer’s intention to go into that phase of the 
subject, as a study of the fully developed aleurone granules can throw but 
little light upon the precise manner of their origin. 
Among those who have given some account of the origin of the protein 
granules in Ricinus are Pfeffer (1872) and Wakker (1888). 
According to Pfeffer (1872, pp. 516 - 87 ), the protein crystalloids and 
globoids appear in the earlier phases of their development as soon as the 
seed-coat has become reddish brown in colour. The cell contents become 
turbid by the presence of oil-drops and albuminous matter. This granular 
material is distributed uniformly in the cell-sap, or accumulated about the 
nucleus and in the plasmic strands. Immediately following this condition 
small starch grains are to be seen in the cell-sap, which, however, soon 
disappear. Pfeffer refers to this starch as transitory starch. With the 
disappearance of the starch other bodies are seen which have become more 
accessible to observation, because of the disappearance of the starch and 
because of an increase in size. There are now to be recognized spherical 
structures, the globoids and the sharp angular crystalloids. As the latter 
increase in size, they are seen to agree in form with the crystalloid of the 
ripe seed. During the ripening of the seed the gradually enlarging globoid 
and crystalloid lie near each other or in contact in the turbid cell-sap rich 
in fat. Pfeffer does not, however, trace the formation of the crystalloid to 
a definite organic primordium, but, according to his explanation, the 
globoid of double phosphate of lime and magnesia first appears, which 
then becomes a centre for the formation of protein material. ‘ Das 
Nebeneinanderliegen der Krystalloide und Globoide findet vielleicht dadurch 
seine Erklarung, dass mit der Bindung von Phosphorsaure an Kalk und 
Magnesia die Ausscheidung derjenigen Proteinstoffe veranlasst wird,welche 
zum Wachsthum der Krystalloide verwandt werden . 5 
Both globoid and crystalloid, according to Pfeffer, attain full size about 
the time the funiculus has begun to dry. Up to this time he did not 
observe the vacuole-like space in which these structures usually lie, and 
which he called the ‘ Hiillmasse ’, formed by the withdrawal of water in the 
