360 Mot tier. — On Certain Ptastids , with Speciat Reference to 
leucoplasts. It is suggested here that these objects represent oil plastids 
or what remains of them. The oil, being miscible in absolute alcohol, j 
has, of course, been removed in large part from the cells. In Ricinus 
there are no elaioplasts present such as has been described by Beer (1909) 
and earlier investigators. These bodies seem to be more numerous than 
the transitory starch grains appearing earlier. It may be asked within 
reason whether leucoplasts are able under certain conditions to synthesize 
oil as well as starch. 
In the parasite Conopholis , the large rounded bodies giving a pro- 
tein reaction can be traced with precision to pre-existing primordia, dis- j 
tributed in the cytoplasm as very small granules or rods. 
In view of the question raised in the paragraph preceding the last 
it may not be out of place to call attention to a marked similarity be- 
tween leucoplasts and chloroplasts. Schimper (1880) was perhaps among [ 
the first to point out concisely this similarity. The following is a trans- 
lation of his summary on the subject : ‘The results of this brief study show 
that the deep chasm hitherto supposed to exist between the starch-formers 
in assimilating (chlorophyll-bearing) and in non-assimilating cells does not, 
in fact, exist. In cells free from chlorophyll there are definite organs which 
generate starch, and these organs are none other than undeveloped chloro- 
plasts ( Chlorophyllkorner ), which under the influence of light are able to 
develop into the latter. On the other hand, chlorophyll grains are not always 
organs of assimilation merely, but they may, in conducting tissues and 
in cells which contain reserve material, function as starch-formers in the 
non-assimilating cells ; they produce starch from assimilated materials 
supplied by other parts of the plant.' 
As applied to certain parts of many plants Schimper’s conclusion 
is correct, at least as far as known. In this connexion it is well to note 
certain differences between leucoplasts and chloroplasts, bearing in mind the 
fact that these generalizations may not apply with equal precision to the 
chloroplasts in all plants. Leucoplasts and chloroplasts originate in 
definite primordia which cannot be distinguished one from the other. 1 
As Schimper pointed out, under certain circumstances one seems to be 
able to change into the other. Both make starch, but chloroplasts can 
elaborate this substance out of carbon dioxide and water, while leuco- 
plasts make starch from the products of photosynthesis. Mature chloro- 
plasts possess the power of growth and division in adult cells. They manu- 
facture and give up their starch successively and repeatedly. In so far as 
the writer is aware leucoplasts cannot divide after reaching maturity. 
When they have elaborated their starch they pass over in that form into 
the permanent vegetative cells. Having reached the adult stage they 
cannot be rejuvenated. 
While these statements seem to be true as applied to many plants, 
