BOTANY. 379 



an exagscratod dovelopineut of the petioles, or may result iu tho perfect develop- 

 ment of the outiro leaf. The iiatiue of the reguhitory mechanism in each instance 

 must be entirely specific. 



''(3) It is possible for some plants to form perfect leaves in darkness, some when a 

 portion of the stem only is darkened, and others when the entire plant is etiolated. 

 It is thus shown that no invariable connection exists between the phototonic condi- 

 tion and leaf development. 



"(4) The conclusion of .Tost, that pathological conditions ensue more (piickly in 

 inactive leaves in light than in darkness, is not capable of general application. The 

 deterioration in certain plants appears as quickly in darkness as in others in light. 



"(.")) riaciug a leaf under such conditions that it can not construct food material 

 sets in motion the specific regulatory mechanism of the organism iu such manner 

 that the plastic material may be withdrawn and the organ cast off. An exaggerated 

 develoiinu'ut of the petioles may be induced in darkness by this mechanism. 



"(()) Plants may not be entirely classified as to their reaction to an atmosphere 

 devoid of carbon dioxid upon the basis of species, since a given jilant may be capable 

 of developing inactive leaves at one stage of its development and not at another. 

 This is evident upon consideration of the fact that such capacity is entirely depend- 

 ent upon tho availability of the reserve food for this jiurpose." 



A form of apparatus for growing plants in an atmospliere free from 

 carbon dioxid is figured and briefly described. 



Indian cultivated cottons, T. H. Middleton {Agl. Ledger, 1895, 

 Ko. S, Veg. Froduct series, ^fo. 15, xyp. Till, 27, jtJs. 5). — Botanical 

 descriptions are given of about 40 Indian varieties of cotton, together 

 with miscellaneous notes and descriptions of se^'eral others. The 

 author distinguishes between Gossypinm herhaceum and G. hirsutum. 

 It is stated that the G. herhaceum of American authors is not tliat 

 species as described by Linnanis. To this species the name G. hirsutum 

 of Miller is given. Attention is directed to the almost liopeless con- 

 fusion in the synonymy of the cultivated species of cotton. 



Grasses of North America, II, W. J. Beal {Xew York: Henry Holt tf- Co., 1896, 

 pp. I'm, 700, Jigs. 12(':). — This is the concluding volume of tho author's work on 

 the "Grasses of North America," the first part of which appeared nearly 10 years 

 ago. In the first volume the economic and related features were treated, the sys- 

 tematic arrangement and description of species being retained for this part. Stu- 

 dents of agrostology will welcome the ai)pearance of this valuable work, since for 

 the first time there are Itrought together descri)ttions of all known species growing 

 north of Mexico, as well as those collected in Mexico by C. G. Pringlo and Edward 

 Palmer. In handling such a mass of material while actively engaged with other 

 duties, some errors have crept into the work, but these defects are not of sufficient 

 number or importance to greatly atfect the value of the entire work. 



The author has followed the " Rochester code " iu his system of nomenclature, 

 and many new combinations are the result. Opinions will dift'er as to tho ]>roper 

 generic; name in sevc^ral instances, it being a disputed ([uestion whether some of our 

 American grasses maj' not have been wrongly referr<'d. 



Of tho fll2 species described in this work, many of them for the first time, 809 are 

 native and 103 introdmed grasses. In a<ldition to describing all these -species, the 

 geographic distribution of the Graminea- in North America is given, and interesting 

 tables are constnnted showing the ]iro]tortional distribution of the species of many 

 genera in the great divisions of the globe. 



Analytical keys are given for most of the tribes and genera, but the absence of a 

 general key to the family will be noticed. Its plact^ is supplied by brief <lescrii)tiou8 



