288 PHYSIOLOGICAL BOTANY. 



p. 487; 1845, i, p. 349. Report, ibid, ii, p. 417, and 

 in detail, in the Ann. de Scienc. Natur., 3 ser., t. iii, 

 p. 123. Report, p. 150. The external calyx (involucre), 

 is first formed, then the true calyx, from a single piece. 

 A globule next arises in this, which exhibits five tubercles; 

 this soon subdivides into two parts, and thus the flower, 

 even in its youngest condition, is furnished with ten 

 staminal tubercles. Five small folds next appear close to 

 the calyx; these are at a tolerable distance apart, and 

 constitute the commencement of the petals. Hence the 

 flower is at first pentapetalous. The development of the 

 stamens, internally, next follows, according to a double 

 plan, first by concentric circles, which grow inwards, and 

 then by the deduplication of the stamens. They are really 

 situated opposite the petals, but in many Malvaceae, we 

 find that the filaments become elongated above the sta- 

 mens, and form five teeth, which alternate with the five 

 groups of the andrsecium, and thus represent the inner 

 row of stamens. The formation of the pistil varies, and 

 the author admits four different methods by which it 

 takes place. To this subject belong : 



Observations upon the Organogeny of the Flower, and of 

 the Ovary in particular, of Plants having a free central Pla- 

 centa. By M. A. DUCHARTRE. Comptes rendus, 1844, 

 i, p. 1105. Development of the flowers of the Primu- 

 laceae. The calyx is first formed in one piece, not several, as 

 Schleiden states. Five tubercles next appear, from which 

 the stamens are formed; the appearance of the corolla seems 

 to precede that of the stamens, when they alternate with 

 the segments of the corolla; otherwise, it follows after. The 

 pistil appears simultaneously with the corolla in the form 

 of a cone, and the placental tubercle fills up the ovary. 

 The ovary next rises up and forms the style. The summit 

 of the placenta subsequently begins to elongate, and passes 

 into the canal of the style, and is not, therefore, at first 

 connected with the stigma. The report upon this me- 

 moir, by Ad. Brogniart, Ach. Richard, and Gaudichaud, 

 is, on the whole, favorable. 



