656 Chronicles of Science. [Oct., 



feathers on a duck's wing. Mr. Lockyer quotes the following para- 

 graph from a letter recently published by M. Chacornac : — 



" Having had the occasion formerly to observe small pieces of silver 

 bathed in borax, melting under the influence of the blowpipe, I have 

 always in my descriptions compared the ' crystals ' of the photospheric 

 matter to this silver solder in a state of fusion. Of the same opinion as 

 Mr. Dawes, I hold that 'straws' at present are the objects which give the 

 best idea of the appearance of the objects of which the whole solar photo- 

 sphere consists. On the other hand, I do not find that in the many 

 notes, and especially in those of Father Secchi, containing observations of 

 this nature, is mention made of any important phenomena presented by 

 these incandescent ' willow-leaves ' or ! rice-grains.' As it is inherent in the 

 nature of this matter, I will endeavour, as concisely as possible, to state 

 in what it consists. If we observe a 'crystal' of photospheric matter, 

 which is completely isolated and projected on a dark portion of a spot, 

 for instance, it will be seen that for a certain time it diminishes in volume 

 and becomes spotted over with small dark pores ; that it is subdivided 

 into numerous crystals, as if the photospheric matter were being volatilized, 

 or as if there were a reabsorption going on, absolutely in the same way as 

 crystals of sugar melt under a current of steam." 



III. BOTANY AND VEGETABLE PHYSIOLOGY. 



{Including brief Notices of recent Botanical Works.) 



Casimir de Candolle has investigated the theory of a single angle of 

 Phyllotaxis, or leaf-arrangement. He considers the views of Schimper, 

 Bravais, and Martins, and afterwards endeavoiu's to show that the 

 single angle will explain leaf divergence. On the same branch we 

 observe successively a series of Cycles belonging to orders of a less 

 and less high number, in proportion as the axis of the branch is elon- 

 gated and all the successive Cycles correspond to the terms of a series 

 of the form : — 



p r p + n r r -\- (p -f- n r) n' 



q s q + n s s + (q + n s) n' 



These fractions are evidently the successive reductions of a continuous 

 fraction of the form : — 



1 



a + 1 



b + 1 



n + 1_ 



These series of Cycles, which are found in different plants or on dif- 

 ferent parts of the same plant, correspond each to one and the same 

 angle of divergence which the eye detects more' or* less completely, 

 according to the greater or less approximation or condensation of 

 the leaves. We may thus take for the value of this angle either 



