March 21, 1902.] 



SCIENCE. 



459 



the landward than on the lakeward side of 

 that zone. The plants engaged in this se- 

 vere struggle show a marked tendency to 

 mass themselves in solid ranks. Illustrated 

 by lantern slides. The paper is soon to be 

 published in full. 



THIRD SESSION, WEDNESDAY, 9 A.M. 



The meeting was called to order by the 

 chairman, and without further prelimina- 

 ries the reading of papers was resumed. 



C. E. Allen : ' Spindle Formation in 

 the Pollen Mother- Cells of Larix.' At an 

 early stage in the prophases of the first 

 nuclear division, fibrous material is present 

 in considerable quantity in the cytoplasm, 

 at first staining with the triple stain like 

 the rest of the cytoplasm. Soon the fib- 

 rous material shows a tendency to stain 

 deeply blue. It is now seen to form an 

 irregular reticulum throughout the cyto- 

 plasm. The fibers gradually arrange them- 

 selves radially to the nucleus; the shorter 

 ones grow in length until a complete sys- 

 tem of radial fibers is formed, connecting 

 the nuclear membrane with the plasma 

 membrane. These fibers now fold over, so 

 that many of them come to lie parallel with 

 the nuclear membrane, and in time to form 

 a dense felted layer immediately outside 

 the nucleus. From the felted layer, the 

 multipolar spindle and finally the bipolar 

 spindle are formed, substantially as de- 

 scribed by Belajeff and Strasburger. The 

 most important point brought out by the 

 investigation is that there is a fibrous sys- 

 tem whose history can be traced from a 

 reticulated stage to that of the completed 

 spindle. No centrosomes could be seen, and 

 the possibility of their presence as cell or- 

 gans or directive centers seems to be ex- 

 eluded. The changes in the arrangement 

 of the fibrous system seem to be correlated 

 with processes going on within the nu- 

 cleus. 



Bruce Fink : ' Some Interesting Lichen 

 Formations.' The author made some pre- 

 liminary statements regarding our present 

 knowledge as to factors upon which ecologic 

 studies may be based. These factors are 

 physical and chemical structures of sub- 

 strata and the structure of lichen thalli. 

 This introduction was followed by a dis- 

 cussion of some of the more common lichen 

 formations, viz., those of smooth and rough 

 bark, those of the boulders of our prairies, 

 and those of calcareous pebbles or horizon- 

 tally disposed calcareous rocks and cal- 

 careous earth. 



H. C. CowLES : ' Ecological Problems 

 connected with Alpine Vegetation.' Al- 

 pine problems, like all ecological problems, 

 present two aspects, phytogeographic and 

 morphological. Most previous field studies 

 of alpine vegetation have failed to separate 

 distinct phytogeographic ideas. Properly 

 to interpret alpine conditions it is neces- 

 sary to distinguish floristic distribution 

 from ecological distribution. Again, eco- 

 logical distribution has its climatic and 

 edaphic aspects. Alpine conditions have 

 been largely regarded as climatic, and most 

 of the peculiarities of alpine plants, dis- 

 tributional as well as morphological, have 

 been referred to atmospheric factors, such 

 as light, temperature, moisture, air. Per- 

 haps alpine plant forms are in the main 

 to be regarded as the direct result of ex- 

 ternal atmospheric conditions, as Bonner 

 has shown. The distribution of alpine 

 plants, however, is apparently due in large 

 degree to edaphic conditions. The timber 

 line in general may probably be referred 

 to atmospheric conditions, but the marked 

 gaps and oscillations which usually occur 

 are due in a large measure to soil relations. 

 While xerophytes increase in the alpine 

 parts of mountains, it is to be observed 

 that edaphic as well as climatic factors be- 

 come more xerophytic upwards. While 



