382 SCIENCE PROGRESS 



It appears that not infrequently there is a fusion between 

 the egg cell and the ventral canal cell in Sphagnum subsecundum, 

 though disintegration of the latter is also equally common 

 (Bryan, Anier. Jour. Bot.). 



Carter [Ann. Bot.), continuing her studies on the chloroplasts 

 of Desmids, finds that in Staurastriim there is usually a central 

 axis with radiating plates, but in S. tumidum parietal chloro- 

 plasts are always encountered, a condition sometimes found in 

 5. grande. 



Ecology. — An excellent and critical resume of the present 

 position with regard to the Classification of Vegetation units 

 is contributed by Tansley to the Journal of Ecology. The view 

 is expressed that the concept of development is essential for 

 their grouping, and that for the higher units life-form is an un- 

 satisfactory criterion. 



Bonnier {Rev. Gen. Bot., T. 32) has written a further paper 

 on his well-known researches on the growth of alpine plants in 

 lowland districts which he has conducted during the past 

 thirty-six years. The present paper deals mainly with plants 

 raised from seed, and the results in the main confirm the earlier 

 work on transplanted roots. Seed from a single parent was 

 in each case sown in an upland and a lowland locality. Those 

 grown in the former were much shorter, less robust, and 

 attained maturity at an earlier phase of development. Several 

 annual species at high altitudes become perennial {e.g. Poa 

 annua) and even evergreen {e.g. Arcnaria serpyllifolia, Echium 

 vitlgare). For the alpine species there appears to be an optimum 

 altitude at which the vigour of the plant attains a maximum. 



A large number of interesting papers have appeared recently 

 dealing with the subject of soil acidity and the action of 

 calcium. Several of these which have appeared in Soil Science 

 are of considerable ecological importance. Neller finds that 

 for Sassafras loam the oxidising power of the soil varies inversely 

 with its lime requirement, and that the crop yield is closely 

 correlated with oxidising power. Parker and Truog find a 

 close relation to obtain between the calcium and nitrogen content 

 of plants, and find that a high lime requirement appears to be 

 associated with a calcium-nitrogen ratio. Shedd, who has 

 investigated a number of virgin and cultivated soils in Ken- 

 tucky, finds that the poorest contain the lowest content of 

 calcium, and the best the highest. The work of Greaves 

 appears to confirm that of Brooks as indicating an antagonistic 

 action between calcium and magnesium. 



The eff"ect of climate on the development of annual rings 

 in Sequoia gigantea is the subject of a paper by Douglas, who 

 regards them as an indicator of the resultant of the sum total 

 of climatic conditions {Ecology). It is suggested that, by the 



