949 



may always remain in use, even when these parts secrete no fluid ; 

 first, because it is acknowledged by almost all descriptive bota- 

 nists, and also, because even anatomists have retained this expres- 

 sion, where no secretion takes place, e. gr. ' glandular conglobatae.' 

 The word nectary may always be retained as a general name ; but in 

 descriptions it would be better to say fossae nectariferae, &c. 



On the ^ liivolucra^ in Cynosurus and Setaria. Dr. H. Koch ob- 

 serves " that the so-called involucrum of Cynosurus consists of sterile 

 spikelets, is apparent to the eye, and has been already recognized by 

 many. The so-called setae of Setaria are peduncles, whose flowers 

 have not attained to perfection. The author shows this in detail, and 

 then adverts to the distinctions between Setaria viridis, italica, and 

 verticillata. He states in conclusion that simple alternation is con- 

 fessedly in the grasses the fundamental arrangement, from the leaves 

 up to the stamens, which are almost always arranged by threes. 

 Our Setariae, he continues, present the interesting fact, that the tran- 

 sition, the fluctuation between the two numerical proportions (the 

 occurrence of twos or of threes), is not confined, as in the other grass- 

 es, to the contrast between flowers and leaves, but appears even in 

 the distribution of the branches. Although the endeavour to give 

 predominance to a divergence of one-third is sufiiciently well marked, 

 yet it is never completely established ; for not only, as frequently 

 occurs, do the primary branches, at the commencement and end of 

 the spike, revert to a divergence of one half; but all the secondary 

 branches up to the last, the peduncle, again exhibit a transition from 

 one-third to one-half, and the latter divergence continues thencefor- 

 ward, as is usual in double flowers and their parts ; so that the Seta- 

 riae change their order of arrangement twice, whilst other grasses do 

 so for the most part but once. 



" In the leaves of most grasses we see indeed the arrangement in 

 threes, for the alternating leaves are in general only a contracted 

 whorl. There is also another circumstance connected with the in- 

 florescence constituted by the peduncles, viz., the antecedence (Pro- 

 lepsis), the earlier or later development, and of this the author has 

 taken no notice. The expression divergence is very unsuitable, and 

 the author himself speaks of the casual magnitude of the angle. 

 Most morphologists interchange the terminology of descriptive with 

 that of morphological botany, which has quite another field. ' Invo- 

 lucrum' signifies the arrangement of parts, external and inferior to 

 the floral sphere, either around a single flower, or around several. 

 What is the character of these parts, considered morphologically, has 

 Vol. II. 6 c 



