230 The Plant World. 



tion have broiijilit to lijiiit. r>otanists who hare occasion to 

 draw ronclusioiis rcoardino plant life in arid or semi-arid 

 re.ii'ioiis will tiud it es^icntial to become conversant with the 

 antlior's arjinments and couclnsions, which seem likely to 

 lead to important modifications of doctrines that have 

 been wid(dv h(4d ami tanu'ht. — V. M. Spalding. 



NOTES AND COMMENT. 

 Tbe resnlts of a carefnl examination of the histolooical 

 relations of ('u.sciitd and S<ilria, one of its hosts, has been 

 published in a i-ecent nnmber of Annals of Botany (Jul.y, 

 1911 I by M. (i. Thoday (nee vSykes). The lack of under- 

 standing of the actual physical relations of plants dis- 

 play('(l i!i this arti(de may be best illustrated by the follow- 

 ing citations from the summary: "The protojilasm of the 

 parasite is easily shrnnk away from the sieve area, and is 

 probably nevci- (los<dy fused with the host protoplasm. 

 The ti'anslocation of food-substances from host to parasite 

 would ai)pear to be of the nature of passive filtration, the 

 contents of the sieve tubes, forced by internal pressure, 

 escaping throuinh the lateral sieve fields into the parasite. 

 This arranjL>ement ])robably disturbs as little as possible 

 the n«)rmal me(dianics of the sieve tubes of the host and 

 ensures for the jiai-asite a lonii-continued supply of nutri- 

 ment." I'nrther "That the i)arasite takes so much trouble 

 to nmke nse of ilie host sieve fields as they are, and not to 

 distni-b the meidmnics of the sieve tubes, is important testi- 

 mony in favor of the functional etiiciency of sieve tubes in 

 general and sieve fields and sieve plates in particular." 

 Tlie^e statements are abundantly refreshinu; both as to lit- 

 erary construction and as to scientific point of view. The 

 actual work on which they are based was well planned and 

 lacks m)thin_ij as 1o thoroughness and exactness. The 

 advance of knowledue concerninn- hydrolysis and kindred 

 processes has made ])ossible a substantial addition to the 

 onrlier results on the subject, ])ublished by Peirce in 1893 

 ami 18!)4.— 1). T. :\r. 



Professor Adolfe Prunet, Associate Director of the 

 Agricultural Experiment Station of the University of Tou- 



