December i, 1883.] 



THE TROPICAL AGRICULTURIST, 



4SS 



VI) aud tlierefoi-e only iu part the var. Ledgeriana 

 of 'Weddell and the 0. Ledgeriana of Moens. In fact 

 it is a picture (phite IV) merely, selected it would 

 seem by Mr. Ledger as the most like what 

 be remembers or supposes these " Rojo " trees to be ; that 

 is all. This plate represents a robust plant with large 

 erect flowers ! 



But Mr. Howard's restricted " Ledgeriana " is still further 

 narrrowed down. Plate IV. happens to have been made 

 from a short-styled pl.ant, and it chances that AVeddelTs 

 diagnosis was also drawn up from one. Mr. Howard prefers 

 with the natives to call this form " macho," and really 

 beUeves that it is male in some more especial manner than 

 the long-styled form, which the untutored Indiins and he 

 term *'herabra" or female. It seems scarcely credible 

 that he can seriously propose to restrict hi.s var. Ledg- 

 eriana to the short-styled state, but he distinctly says 

 that '* it is exclusively the macho form." Mr. Howard 

 has been led to the rednctio ad absurdum of giving a 

 definite botanical name to a mere sexual condition prob- 

 ably incapable of self-fertilization, simply on the faith of 

 Mr. Ledger's opinion as to plate IV. The latter gentle- 

 man (or rather his native servant) was also much struck 

 with the odour of another plate (tab. X.) represent- 

 ing the hybrid " 0. anglica." This reminded him 

 of the colour of the " rojo " and Mr. Howard at once 

 jumps to the conclusion that the two are " very nearly 

 related "; but as this plate X. happens to be drawn 

 for a long-styled form, or is very decidedly "hembra" 

 as Mr. Howard puts it, it " cannot come under Weddell's 

 diagnosis." 



"We may, however, feel, very certain that Dr. M''eddell, 

 in 1875, when he drew up the definition in question was 

 not intentionally creating a variety on what was then well 

 known to be a merely physiological condition ; to support 

 the position that he did so, Mr. Howard quotes remarks 

 written by that excellent botanist in 1849 when the nat- 

 ure and relationships of dimorphic flowers (so frequent 

 in Ruliiaceif) were not properly understood: it is note- 

 worthy that in 1869 Dr. AVeddell had deliberately dropped 

 the liark-cutters' term "macho," which he then no doubt 

 saw to be misleading. 



One sees with regret throughout all these communic- 

 ations of Mr. Howard a very remarkable neglect, or an 

 intentional defiance of the accepted rules of botanical 

 nomenclature. For iustance, he makes the astounding 

 remark that " it belongs to Mr. Ledger aud to him alone 

 to define what is the true Ledgeriana." AVhy? on 

 what possible grounds? Mr. Howard has said a little be- 

 fore, and fairly enough, that " the privilege of naming a 

 plant belongs to the botanist who first obsej'ves and 

 properly describes it" ; this may pass, but how in the 

 world can it apply to Mr. Ledger ? 



In conclusion, a few words as to the Oeylon cinchonas 

 spoken of by Mr. Howard. He has committed himself to 

 the following identifications:— (1) The plant figured by me 

 = 0. micrantha, rar. calisayoides (probably) ; (2) Mr. 

 Christie's specimens {SSt. Andrew's E-tate) ^ c'. calisaya 

 var. microcarpa but probably hybridized with "0. ofiic'i- 

 alis) ; (3) Sir. Laurie's (Yarrow estate) = C. calisaya, var 

 "Ledgeriana." Now, I am familiar with all these. 'They are 

 all from the same small quantity of seed and were raised 

 in the same nursery beds at the same time; aiid I can 

 state positively that they are ciJ.l hotanicalli/ identical. Further, 

 they are also identical with what is and always has been 

 known as " Ledgeriana" iu Java ; aud, as " Ledi'eriana" 

 (species or variety) was founded on the plants In Java 

 and has never yet been applied to any wild South American 

 tree, the Oeylon plant must of course bear the same name 

 I regi-et the quantity of ink shed over so simple a matter. 

 Peradeniya, Ceylon, 29th October 1883. 



INSECT ENEMY OF OEANGE CULTIVATION 

 IN BRITISH GUIANA. 



Downing Street, Jth September. 1883. 



Oeylon No. 307. Sir, — I have the honor to transmit to 



you herewith a copy of a report by Mr. R. McLachlao, 



F. R. s,, upon an insect which has attacked the orange 



plautation.s of British Guiana. 



As scale insects infest many kinds of plant in.OeyloM, 



the information contained in this report may be found of 

 use in the colony. — 1 have fcc., ("Signed). Deebt. 

 Lieut.-Governor Sir Jo;in DonGLAS, k.c.m.g., etc., etc. 



Mr. MoLachlan to Sir J. Hooker. 

 Westview, Clarendon Road, Lewisham, London, S. E,, 



23rd Aug. 1683. 

 To Sir J. D. Hooker, k. c. s. i. f. e. s., etc., etc. 

 Director of Eoyal Gardens, Kew. 



Dear Sir Joseph, — I have the honor to report on certain 

 portions of branches of orange from British Guiana for- 

 warded through the Colonial Oflnce which are greatly 

 infested with a " scale insect" or " coccus." 



The insect in question belongs to the (genus) of coccida 

 termed Diasjiis and as it did not appear to accord with 

 any previously described species of that (genus) I for- 

 warded it to my friend Dr. Victor Signoret of Paris, 

 who has made the systematic classification of coccida his 

 special duty. He is of opinion that it is undescribed, 

 and has recently, I believe, bestowed upon it the name 

 " Diaspis durantie." 



Three samples of portions of branches were submitted 

 to me labelled respectively "orange" Bhal (?) and''Hme": 

 of these the orange appears to be the least affected and 

 the " lime " the most, but in all cases the scales are so 

 thickly placed as to nearly ob.scure the bark. The same 

 species of "scale" infests all three, but at first .sight there 

 appear to be two differeiit kinds, one large and dark in 

 colour the other much smaller and whitish. The larger 

 "scales" are those of the female insect, the smaller tbose 

 of the male. 



The life history of scale insects may be briefly stated 

 as follows : — 



The eggs (which are very numerous) are deposited by 

 the female under the scale she has secreted and under which 

 she herself lives for the greater part of her life. These eggs 

 soon hatch (the time varing according to the temperature) 

 and the young larvre wander forth. This period of activity 

 is of very short duration probably never more than a day 

 or two aud at its end the larv.-e settle down on some portion 

 of the plant affected aud commence secreting the " scales" 

 under which the fem.ale lives for the whole of her remaining 

 existence and the male until it is ready to assume tlie per- 

 fect state in which it is a very minute wliitish two-winged 

 insect (but in many species of Coccida, the male is unknown 

 and the generative condition known as " parthenogenesis" 

 probably obtains). In hot climates, such as British Guiana, 

 it is probable there may be three or four generations iu 

 each year, but this can only be determiued by local observ- 

 ation. It is of importance that the short period of activity 

 immeiliately after emergence from the egg should be borne 

 in mind, for it is possible that at this period the insect 

 can be more readily atttacked by remedial measures. 



Remedies may be mainly sought under two categories 

 "mechanical" and "insecticides," and in connection with these 

 I woulil earnestly advise those interested in orange culture 

 in British Guiana to consult the report of the entomologist 

 of the United States Department of Agriculture for the 

 the year 1880, by J. Henry Comstock (1881), aud the re- 

 port of the entomologist from the annual report of the 

 same department for the year 1881, by Charles V. Riley 

 (1882), both issued from the Government Printing Office 

 at "Washington. Both may lie consulted with advantage, 

 and the more so as the two authors did not work in 

 concert, and their ideas are not always identical in the 

 means proposed. In Professor Eiicy's report he has been 

 aided by the practical experience of Mr. H. S. Hubbard, 

 who devoted himself especially to the subject. In the 

 Southern United States the attacks of " scale " on oranges 

 has become of national importance and experience there, 

 and in British Guiana should be nearly identical, although 

 the particular species of scale insect injurious in the 

 British Colony does not appear, to have been observed in the 

 States. 



Of mechanical measures, one of the most important i.s 

 that of brushing the ports of the trees infested with a 

 brush sufficiently strong to remove aud destroy the scales 

 without injuring the hark. It must rest with orange 

 planters iu the districts affected to consider how far this 

 can be successfully done, iu.which the height of the trees 

 and the comparative freedom from scale of the leaves aud 



