l 7° BOTANICAL GAZETTE [nmji 



\RY 



ideal of the corn-breeder should then be continuous hybridization between 

 biotypes, rather than the isolation of pure strains.-R. R. Gates. 



Isolation and mutation.-While the final adjudication of the claims of the 

 various theories of evolution must be made on an experimental basis, such data 

 must be m harmony with the facts of plant and animal distribution, as is pointed 

 out in a suggestive paper by Leavitt. *4 It is of much interest t0 obm ^ 



zoologists, as a rule, have been less inclined to believe in mutation than have 

 botanists. Thi* c ;« ^ n *+ j... T .. . , 



Leavitt 



t\u*~ u , , r ' JJILAVUi LiiinKs, to a less perfect grasp ot the 



theorj by some of the zoologists, but in part due also to the fact that most students 

 Z^T . dlStnbution believe tha t isolation of closely related species is a most 

 ZZ T P ? C1P ^ evolution - The author shows that there are innumerable 



ttW? . P m Cl0S6ly rekted Plants of a11 g rou P s > most notable . Frhaps, in 

 widely vary mg thallophytes and bryophytes, but abundant in the seed plant 



wither y u° f eVidenCC that new s P ecies ma y hav « originated from the old 

 Therefl^f^ ° n ' alth ° Ugh Cases su gS es «ng the latter are not wanting, 



the™- £ ", ls 1 conduded » man y facts of plant distribution favor the mutation 



H C Cowle d ° n0t Sh ° W ^^ thiS iS thC ° nly VaM thC0ry ° f evolution " 



BL C. Cowles. 



ertie?rf 0t !n Pr ° Pert ii eSOf r °° thairS -~ HlLL25 has inve stigated the osmotic prop- 

 herbacea W h** ° f Glyceria m ^itima, Suaeda maritima, and Salkomk 



sure of it^-l gr ° W , in E Sdt marsh Sub J* ect t0 g reat chan g es in *e osmotic P* 3 " 

 ing rains H fi 'h *° Peri ° diC fl °° ding h ? the tides and to occasional drcnch - 



osmotic pressure rnrr! hat ^ ^ Sh ° W marked and rather ra P id ^^ ^ 

 water Th T • COrres P° ndin g m variation to the osmotic pressure of the soil 



soil water f Vanatl ° n ^ dUC t0 the entrance of the abundant chlorids of the 



could be found' 11 T ^ ° 0Uld ** ^ ChI ° rids in the root hairS ' aIth ° Ugh ^ 

 pressure of th '" 'l S " ** UPPCr V° nions of the seedKngs. The high osmotic 



sou water seems to act through the irritability of the protoplasm, 

 issociation of the compounds of the cells. He thinks Osterhout is 



.111 I II 11 V"\ ■#"!• A- La. J K 



m^tt*; ?-*=«-££ 



■I 



the fact that n| a of this inv estigator can be explained d 



in protection a^W ""^ ** ° Sm ° tk pr0pertieS readil y in reSp ° nSe * ^ 

 Crocker. fapidIy Var >' in S externaI osmotic pressures.-^"* 



** of well chole^ r '~ BDDER * 6 comes to the support of the statolith theorj' wits a 

 _ n and cntical experiments that seem to justify his conclusion? 



24 Leavitt R <; t*u 



Nst 41:207-240. '^ g eo ^aphic distribution of nearly related species. Amer- 



25 Hill, F G Oh 



tain salt marsh plants 5 Vat '° ns on the osmotic properties of the root hairs of cer- 



* 6 Buder w " ewPhytol °g ist 7: 133-142. 1908. 

 ^rFei>rrles 2 c-1ahriln^ L " tersuchun gen zur Statolithenhvpothese. Festschrift 



5 JaHngen Bestehen * *r Deutsch. Bot. Gesells. Ber 2 6:i6 2 -i 9 3- ** 



