74 BOTANICAL GAZETTE [JULY 
at Peradeniya occurs in the driest part of the year (all of which is very wet). 
To account for this, he suggests that it is only in the drier period that the trans- 
piration stream can supply enough salts! Then on this assumption he erects 
another: ‘“‘If this be the case, the higher internal temperature attained by the 
coloration of young leaves would promote the some object, viz., the increase of 
the transpiration stream.” All of which is an excellent example of spoiling 
good observations by bad logic.—C. R. B 
Sex in dioecious plants.—A study of the two mitoses by which the microspores 
are formed from the mother cell in Acer negundo has led DARLING’? to interpreta- 
tions and conclusions about which there may be considerable difference of opinion. 
He finds that all the chromatin of the resting nucleus of the microspore mother cell 
is contained in the nucleolus. Chromatin from the nucleolus diffuses upon the 
linin and in this way there is built up a spirem which segments into eight chromo- 
somes. Later, five more chromosomes are formed from the nucleolus, so that, all 
together, there are thirteen chromosomes formed in these two ways. After the 
second mitosis, two of the daughter nuclei differ from the other two in containing 
one more chromatin mass, but when the resting stage is reached, the four nuclei 
look alike. 
The writer believes he has found something somewhat analogous to the matura- 
tion mitoses in some insects, and that the peculiarities in Acer negundo have some 
connection with the determination of sex. 
The fact that the division of the chromosomes at the Acaiad mitosis could not 
be determined with certainty would indicate that the technic was hardly sufficient 
to establish the claim that the eight and five chromosomes originate differently. 
The problem, however, is important and the presentation of results suggestive— 
CHARLES J. CHAMBERLAIN. 
Chlorophyll of seeds.—MonTeveRDE and LupimeNnko, working independ- 
gaa have arrived at the same conclusion regarding the green pigment of the 
of thirty-eight Cucurbitaceae, viz., that it is not chlorophyll, but that it 
mbles the protochlorophyll of ciolaied leaves.'8 Yet neither in the living 0° 
ae dead hulls does it go over, under the influence of light, into chlorophyll. It 
appears rather late in the development of the seed, in chromatophores which are 
indistinguishable from chloroplasts and may even contain ade also. Its 
absorption spectrum differs in certain details from that of living green leaves: 
They propose to call this new pigment chlorophyllogen, retaining the name 
protochlorophyll for the optically altered chlorophyllogen which one can observe 
in dead tissues and neutral solutions. This chlorophyllogen becomes transformed 
into chlorophyll under the influence of light plus some other yet unknown facto! 
17 DARLING, CHESTER ARTHUR, Sex in dioecious plants. Bull. Torr. Bot. Club 
36:177-199. pls. Lege Ig0o9. 
t8 MonTEVERDE, N., uND LusmMENKO, W., Ueber den griinen Farbstoff der 
inneren Seneahatie einiger Cucurbitaceen und dessen Beziehung zum Chlorop hy 
Bull. Jard. Imp. Bot. St. Petersbourg 9: 27-44. 1909. (Russian: German résum® 
sag 
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