September 1, 1898.] 



KNOWLEDGE. 



211 



occasional darkening of portions of the leaves (Fig. 11), 

 and always the presence of minute pellets of frass, which 

 are forced out at the aperture at the tip of the shoot, and, 

 falling, rest in the axils of the leaves (Fig. 11). Directly 

 these signs are noted any of the shoots so affected, on 

 being split up, reveals " the miner " — plump and fat — with 

 plenty of room to move up and down. All shoots contain- 

 ing a maggot have (as shown at Fig. 12) the centre eaten 

 clear away, and all chance of fruit-bearing is gone. The 

 larva sometimes leaves its burrow and pupates among the 

 dead leaves at the base of the shoot, but it generally 

 remains inside to undergo its change. The pupa has rings 

 of minute spines around the margins of the segments, by 

 the aid of which it can lever itself up to the top of the 

 shoot, from which the raspberry moth emerges in the 

 course of a week or two. 



The great point to bear in mind in connection with this 

 raspberry pest is that it remains but a few weeks in the 

 shoot, and that it is there the latter part of May. This, 



I 



BOTANICAL STUDIES.-V. 



ASPLENIUM. 

 By A. Vaughan Jennings, f.l.s., f.g.s. 



N the moss plant which formed the subject of our last 

 study '■ we found that, as in Junijermannia,f the life- 

 history consisted of two distinct stages. It was 

 observed that the leafy moss-stems of Mnium carried 

 more or less evident "flowers" at their tips. 



Fia. 12. — Section of Raspberry Shoot showing larva of Laiiiproiiia 

 rubiella. 



then, is the time to destroy it, which must be done at the 

 sacrifice of many canes, or even the whole crop. When 

 the moths have escaped — in early June— it is impossible 

 to prevent eggs being laid by them for the next season's 

 brood. Catching the moths (in exactly the same manner 

 as by entomologists) would materially lessen them if carried 

 out in a systematic manner, and untU some such work is 

 carried out these insect miners will go on increasing. 



Fruit and flower growing has now been brought up to 

 great perfection, but we are still far behind in systematic 

 work for coping with insect pests. 



Knowledse, July, 1898. 



t Knowled&e, May, 1898. 



containing either the egg-bearing Archegonia or the 

 fertilizing Antheridia ; and that from the former there 

 arose the slender stalk and drooping capsule which 

 we know as the " moss-fruit." In other words, that 

 there was a green, leafy Oophijte, or egg-bearing plant, 

 from which grew a distinct type of plant, the Sporophyte, 

 whose spores in turn developed the form of the parent 

 Oophyte. 



Bearing this in mind, and looking among the higher 

 flowerless plants, such as the ferns and their relatives, for 

 a type to study in continuation of our series, we should 

 come to the subject with preliminary expectations that will 

 cause us some trouble. Naturally enough we shall expect 

 that a fern, say the little spleenwort here figured (common 

 in the crevices of stone walls), may be regarded as a plant 

 comparable to a moss-plant, though of much higher 

 development and greater complexity of internal structure. 

 We shall look at the fronds expecting to find something 

 equivalent to the moss " flowers," and showing under the 

 microscope more or less similar groups of Archegonia and 

 Antheridia. 



It will be found that the only structures on a normal 

 frond which suggest a fructification, are the oblique lines 

 on the under surface of its pinnse ; light coloured in the 

 young plant, but larger, browner, and dust-like on the 

 older parts. If we cut a thin section with a razor across 

 one of the younger pinna?, we shall find something similar 

 to the central figure in the illustration. A number of oval 

 bodies borne on longer or shorter stalks, rising from super- 

 ficial cells of the leaf, though partly covered by a thin 

 irregular membrane rising from one side. The oval bodies 

 have evidently a distinct celliJar wall, and the older ones 

 enclose a mass of dark granular cells in a condition of 

 active division. There is evidently nothing that can be 

 compared to an archegonium. What, then, are these struc- 

 tures '? Are they antheridia '? It seems not improbable 

 from their appearance when young, but an examination of 

 the older ones will not confirm the idea. If we take one 

 of the older pinn.-e and scrape off the brown material from 

 the under side, we find the structures shown in Figs. M 

 and N. They are stalked, thin-waUed cases, with a dark 

 layer of thick cells running round some two-thirds of the 

 margin ; in the interior is a dark mass which, when a ripe 

 case bursts, resolves itself into a number of brown bodies 

 with thick, rough walls. There is, evidently, nothing here 

 like the minute, free -swimming bodies we saw discharged 

 from the moss antheridium ; but, on the other hand, these 

 bodies have a strong resemblance to the spores of the moss 

 and the liverwort. 



It is, in fact, evident that the oval cases are Sporawjia , 

 but are they equivalent to the spore-capsule of Mnium or 

 Junijermannia .' If so, they are very minute and simple 

 in structure ; and, further, should be found to arise from 

 fertilized archegonia. Referring again to the section, or 

 making new preparations, no trace of archegonia can be 

 found, and it is evident that some different line of study 

 must be adopted. Suppose we "plant ' the spores and 

 see what becomes of them. 



If a number of the spores are scattered over a layer of 

 mould or on the side of a flower pot, and kept moist, it 

 will soon be seen that the surface is acquiring a green 

 colour, and a pocket-lens wiU show that this is due to the 

 growth of a number of separate little green discs. Under 

 the microscope these may be seen distinctly to originate 

 from the germinating fern-spores. At first they are 

 merely narrow plates of chlorophyU-containing cells, but 

 by the continued division of a triangular cell at the tip, 

 and by the rapid growth and division of cells at the side 

 of it, a heart-shaped or bi-lobed structure is ultimately 



