Nov. 1, 1870.] 



HARDWICKE'S SCIENCE-GOSSIP. 



25 L 



The force of this difficulty is increased by the 

 consideration of a specimen I have lately found, in 

 which there is undoubtedly a suppression of an in- 

 ternode ; it is a strong vigorous shoot.of the Clema- 

 tis, having apparently four leaves in each whorl. 

 Closer examination showed that this was not really 

 the case; for, instead of the expanded petioles 

 forming an uninterrupted line clasping the stem, as 

 in the three-leaved form, the leaves were in pairs, 

 one pair slightly in advance of the other, though so 

 close together as to present quite a cruciate appear- 

 ance. This arrangement continued for nearly the 

 whole length of the shoot. In this form, the stem 

 was six-grooved, and resembled in every respect the 

 ordinary form. 



These considerations suggest the following view 

 of the structure of a stem, which, would, I think, 

 give a fair explanation of the arrangement of leaves, 

 both in alternate and whorled-leaved plants. A stem 

 may be considered as consisting of a number of ele- 

 ments, capable of producing leaves, arranged round 

 a central column. In plants with alternate leaves, 

 the number of these elements equals the number of 

 leaves in the complete spiral. In verticillate, in- 

 cluding under this title opposite-leaved plants, it is 

 double the number of leaves in each whorl. In the 

 former case, the elements develop leaves singly, 

 taking their turns in a regular order. Thus, in the 

 very common arrangement which exists in the 

 Cherry, &c, there are five such elements, which 

 develop leaves in the order 1, 3, 5, 2, 4. In the 

 latter case all the alternate elements develop leaves 

 simultaneously at every other node. Thus, in a three- 

 leaved branch there are six elements, of which 1, 3, 

 and 5 develop leaves together, and 2, 4, and 6 at 

 the next node. It may be objected to this view that 

 the number of leaves in a whorl is often by no 

 means uniform. Thus in the Great Bedstraw 

 {Galium Mollugo) the leaves, though normally eight 

 in a whorl, are often only seven, six, or even five. 

 It would, however, appear not improbable that out 

 of so large a number crowded together, and perhaps 

 with a deficiency of nutriment, one or more elements 

 might occasionally miss developing a leaf in their 

 turn. I have lately found a specimen of an irregu- 

 larity which may perhaps partially bear out this 

 view ; this is a shoot of clematis, three-leaved up 

 to a certain point. Then occurred a node with two 

 leaves simultaneous, but not opposite; about an 

 inch higher was a single leaf, so placed as to com- 

 plete the whorl; this arrangement, alternately of 

 two leaves and a single one, continued up to the 

 end of the shoot. On examining this stem, I found 

 that it had but eight grooves instead of nine. In this 

 case it would appear as if a slight defect in the 

 structure of the stem had produced a delay, but not 

 an entire suppression of a leaf. 



As an instance of the diminution of the number 

 of leaf-forming elements, I may mention a shoot of 



cornel, in which the leaves, instead of being oppo- 

 site, were alternate and tristichous. In this case we 

 may suppose that, instead of the four leaf-producing 

 elements natural to that plant, there are in this 

 shoot but three ; at any rate, in the tristichous form, 

 three straight lines only can be drawn up the stem 

 through the centres of petioles ; while in the oppo- 

 site-leaved form there are four, and in the three- 

 leaved form six such lines. 



In conclusion, we may observe that all these 

 peculiarities are, as it were, personal to the particu- 

 lar axis in which they occur, and have little or no 

 tendency to be propagated to secondary axes. They 

 thus appear to point to some peculiarity in the 

 original bud from which the axis is developed, and 

 are such as might be most readily explained by the 

 hypothesis of leaf-producing elements. 



EGGS OF BUTTERFLIES AND MOTHS. 



" T WANT pretty and interesting objects for the 

 -*- microscope, for which 1-in. or 2-in. objective 

 is sufficient. They should be such as any one can 

 comprehend— in fact, common objects." Such a 

 requistion we have had, and perhaps some of our 

 readers likewise, and soon found their wits exhausted 

 in the endeavour to recommend something a little 

 out of the ordinary track which should fully answer 

 the requirements. Eggs to the rescue! Here 

 seems to be beauty and variety appreciable by all, 

 and by no means common in cabinets. A child can 

 understand what is meant by the " egg of a moth," 

 or " eggs of the white cabbage butterfly," and even 

 a child would be surprised and delighted to see 

 them under the microscope. 



It seems rather inexplicable how it is that some 

 very interesting and common objects do not meet 

 with general appreciation,— Can it be simply because 

 they are common ? In this category feathers, or at 

 least the "down," might be mentioned. There is 

 considerable variety in the feathers of different 

 groups of birds. Then, again, the eggs of insects, 

 what a very great variety of objects, with features 

 so distinct that any one would recognise them, and 

 yet so few microscopists include a good series in 

 their cabinets. The small seeds of plants have 

 been recommended and figured in this journal, and 

 Foraminifera have had their share of attention, yet 

 quite as much could be said in favour. of eggs, and 

 still eggs are almost forgotten. In order to awaken, 

 if possible, a little interest in these organisms, we 

 have selected a few for illustration, accompanied 

 with brief notices. These all belong to the Lepi- 

 doptera ; but the eggs of insects belonging to other 

 orders are, many of them, scarcely less interesting. 

 The illustrations we furnish of the eggs of British 

 butterflies are types of the principal groups. In the 

 closely-allied species, many of the eggs are very 



