362 BOTANICAL GAZETTE [MAY 
and blue-green algae, are of great importance in marl formation. The cal- 
careous incrustations, which give rise to marl upon the decay of the plants, are 
formed by the deposition of CaCO; when the CO,, which caused it to remain 
in solution, is used in photosynthesis. The oxygen set free in photosynthesis 
also causes the precipitation of CaCO;. One interesting fact brought out by 
the study is that plants vary widely in respect to the incrustations, aes 
selective processes not yet understood.— H. C. COWLES. 
Miss ELizABETH DALE, in a communication to the Royal Society, 
London, through Professor H. Marshall Ward, shows that the abnormal out- 
growths, or intumescences, in A/zbiscus vitifolius Linn. are due to patho- 
logical conditions, being formed in a moist atmosphere, provided there is 
also adequate light and heat. The immediate effect of the damp atmosphere 
is to check transpiration. This, in its turn, by blocking the tissues with 
water, disturbs the normal course of metabolism, and so leads (when the 
light and heat are sufficient) to abnormal development of certain regions. 
The formation of these outgrowths is accompanied by the production of oil, 
which is not found in normal leaves. Its presence suggests that events 
similar to those occurring in succulent plants are taking place, viz., reduced 
respiration and the development of osmotically active substances in excess. 
It is therefore probable that the intumescences are due to the local accumula- 
tion of osmotically active substances, produced under the abnormal con- 
ditions.—H. M. WarpD 
THE LITERATURE of the first mitosis of the spore mother cell of Lilium 
shows a wide divergence of opinion in regard to the phenomena involved, but 
there aré certain stages which have been constantly observed. How these 
stages are derived from one another is the most debated question. Ina 
recent paper Professor Dixon™ figures and describes six well ascertained 
stages, and then proceeds into the debated territory. Nearly all observers 
describe a longitudinal splitting of the entire thread just before the seg- 
mentation into chromosomes, but Professor Dixon believes that the stage S0 
constantly observed arises from the looping on each other and approxima- 
tions of two portions of the thread. Several very suggestive objections are 
urged against the commonly accepted interpretation. Although believing 
that each of the two twisted portions undergoes a longitudinal splitting while 
stillin the spirem stage or immediately after differentiation into chromo- 
somes, regarded as a second longitudinal splitting by Guignard and others, 
the author believes that this is the first and only longitudinal splitting. A 
series of very clear diagrams illustrates the author’s interpretation of the 
composition of the chromosomes and their behavior during the later phases 
4On the first mitosis of the spore mother cells of Lilium. Notes from the Botanical 
School of Trinity College Dublin 4: 129-139. pls. 7-8. 1901 

