CURRENT LITERATURE 339 



added. 



The work is a notable contribution to our knowledge of the flora of 



4 



Madagascar— J. M. Greenm 



North American Flora-Part 4 of Vol. XXII contains a «*«-*«^ 

 P. A. Rydberg's elaboration of the Rosaceae. The groups treated ar PoUmt a 

 and the related genera. In all sixteen genera are here considered, and to h I 

 author refers , 77 species, of which 70, approximately one-fourth, «£°™£ 

 new. Potentil a leads with , 76 recognized species, 44 being ^edas nc 



to science. Two : 

 J. M. Greexman. 



Lachem ilia) 



NOTES FOR STUDENTS 



Longevity of seeds.-In a long paper* Ewarx classifies seeds accor^ngto 

 their duration of life under optimal conditions as: microbiotic seeds, with a lon^ 

 itvof less than 3 years; mesobiotic, with a longevity of 3 to 15 >ears, 

 blotic, with a longevity of 15 to 100 years. Most of the paper &$*««£ 

 pages) is taken up with a table, drawn from the works of vanou £**££ 

 showing the age, percentage of vitality, etc., of vario us stored a. ^ 

 Ew«r says: « Longevity depends not on the foocL uatenaU £ seed I ^ ^ 

 upon how long the inert protein molecules, into which the nyi 8 l £ ^ ^ 

 integrates when drying, retain the molecular grouping whic pe ^ ^ ^ 

 recombination to form the active protoplasmic molecule wne ^ ^ ^ 



ened and supplied with oxygen." Longevity, however he o ^ ^ 

 tound in seeds with seed coats impervious to water, and asse ^ ^^ 



meability is due to cuticular structures in almost all cases exam • _^ ^ 

 s<mia Agitato, on the other hand, all layers of the coats are equ > 



He agrees with Crocker that seed-coat characters rathe ^J^ 6 ^ he mak( a 

 ters account for the greater number of cases of delayed germin , ^ ^^.^ 

 considerable use of the data of this writer as evidence on this p ^^ Jhe 

 that the longevity of seeds in soil is far less than is genera > ^ conditions 

 maximal duration of the seeds of certain Legummosae un e^ ^ Nymphe aceae 

 is stated to be between 150 and 250 years, and of Mal L -^ t ' he structure 



^tween 50 and 150 years. An appendix by Miss Jean \ h ^ g ^ ^^ by & 

 of the coats of various resistant seeds. The body 01 ^ ef investigators, 



number of inexcusable errors in the statement of the results 

 "~Wm. Crocker. . • f e nzvmes 



Enz yme s.-GRUSS has suggested? a method of capillar) ' _ ^ of th e 

 f <» which he claims considerable value. It consists in pulven g ir 



- — — - 00 New \ork Botanu ai 



5 North American Flora, Vol. XXII, Part 4, PP- 2 93 3»- 



arden ^9o8. RoV SoC . Victoria. N.S. 



6 Ewart, Alfred J, On the longevity of seeds. Woe. j 



2l:i "" 20 - **• *> * 1908. h- Hot. Gesells. 26a: 



6 20-6 26 



908. 



