August i8, 192 i] 



NATURE 



797 



or elongated dorsal fins, but the author does not 

 allude to the slow lumpsucker, which has none of 

 these characteristics. 



Lastly, M. Fage refers to positive and negative helio- 

 tropism in the larvae, the former being illustrated by 

 the capture of the young Capros aper much nearer the 

 surface by day than by night, and the latter by the 



passage of Paracentropristis hepatus from considerable' 

 depths by day to a more superficial area by night. 

 The study of this subject, however, is still in its 

 infancy. Many other interesting features are instanced 

 by the author, whose memoir forms an important con- 

 tribution to the subject of the larval forms of shore- 

 fishes. W. C. M. 



The Lac and Shellac Industry in India.^ 



By Dr. A 



AT the present time India holds what is virtually 

 a monopoly of lac production, and no satis- 

 factory substitute has yet appeared on the world's 

 markets. This monopoly cannot, however, be re- 

 garded as a sinecure ; other countries are likely to 

 be found suitable for lac cultivation, and the present 

 high value of lac and its importance to many 

 Western industries render it urgent tha"t the produc- 

 tion of this substance should be encouraged along 

 im'proved scientific and economic lines. The propaga- 

 tion of lac is still very carelessly carried out, and its 

 methods of collection need much improvement. The 

 crop varies from year to year, prices fluctuate 

 seasonally, and there is much injurious market 

 speculation. The bulk of the world's lac comes from 

 Chota Nagpur, Orissa, the north-eastern half of the 

 Central Provinces, some western districts of Bengal, 

 and from part of the Mirzapur district of the United 

 Provinces. Out of the ninety or more trees which 

 have been recorded as hosts for the lac insect 

 (Tachardia lacca), the most important include 

 Schleicheria trijuga, Butea frondosa, Zizyphns jujuba 

 and xylopyrus, together with species of Acacia, Ficus, 

 etc. These plants contain much gummy or resinous 

 matter or are rich in latex. 



The problems concerning lac production are mani- 

 fold, and may be roughly divided into (i) botanical, 

 (2) entomological, (3) chemical, (4) cultural, and 

 (5) technological. On the botanical side we need 

 more especially to determine the optimum conditions 

 which conduce to the food-plants yielding a heavy 

 crop of lac. It also needs to be ascertained how far 

 it is possible bv cultural treatment to stimulate the 

 plant's production of those substances which are 

 utilised by the insect in lac secretion. On the entomo- 

 logical side the most important problem is to deal 

 with the enormous number of parasitic and other 

 insects which annually destroy a prodigious amount 

 of lac, either directly or indirectly. It is extremely 

 unlikely that any marked improvement in lac culture 

 will result until this complex problem has been 

 thoroughly gone into. On the chemical side we need 

 to know what plant substances are essential as food 

 or raw material for the lac insect. Once the bio- 

 chemistry of this problem is understood, it will pave 

 the way for a better understanding of the require- 

 ments of the insect and open up a whole field of 

 research into the cultural conditions necessary. 



Under the latter heading are many other problems. 



1 H. A. F. Lindsay and C. M. Harlow: "Report on Lac and Shellac." 

 Indian Forest Records, vol viii., part i , 1921. Pp. x + 162 + 4 P'ates+io 

 charts+i map. 



D. Imms. 



Pruning and pollarding are highly desirable, for the 

 lac insect is dependent upon the existence of young 

 shoots in the right physiological condition. The 

 extent and frequency with which the trees can be 

 safely infected to yield the optimum crop need to 

 be ascertained. It is also necessary to acquire 

 definite information whether the best results are 

 likely to be obtained from the establishment of lac 

 nurseries composed of young trees of convenient size 

 under careful cultivation, or whether little benefit is 

 likely to be derived, as compared with the present 

 system of relying solely upon existing trees growing 

 wild and distributed over v^ide areas. On the techno- 

 logical side much improvement is possible ; we need 

 to ascertain the best and most economic methods of 

 dealing with lac in all stages of its treatment — from 

 the condition when it is received as stick-lac up to 

 the final products of shellac, lac-wax, and lac-dye. 

 The present system is primitive and often uneconomic, 

 and adulteration is frequent. 



The problems are highly complex and involved, 

 and this fact is fully appreciated by Messrs. Lindsay 

 and Harlow in recommending that a central lac 

 laboratory be established in India. Under the exist- 

 ing system most of what research has been done at 

 all has been carried out partly by the Forestry 

 Department at Dehra Dun and partly by the Agri- 

 cultural Department at Pusa. Neither of the research 

 institutes located in the above places has the neces- 

 sary staff available for the work. The choice of a 

 site for such a laboratory is likely to prove difficult, 

 as there are many factors to be considered The 

 sine qua non is that it must be located in an im- 

 portant area of lac production, where the problems 

 can be studied on the spot. Such a laboratory would 

 be devoted primarily to the study of the growing crop 

 in relation to its environment. Its first aim presum- 

 ably would be to obtain exact and trustworthy in- 

 formation bearing upon the many problems involved. 

 At the present time we need new ideas and trust- 

 worthy knowledge. Much that is published is largely 

 a repetition of what has appeared previously; the 

 same statements, and often the same errors, have re- 

 appeared with perennial regularity, and little or no 

 real progress has resulted. Messrs. Lindsay and 

 Harlow's bulletin is a useful resume of the present 

 position of the problems concerned, and the sugges- 

 tions which they bring forward will, it is to be hoped, 

 receive the fullest consideration by those whose duty 

 it is to develop and influence our means of utilising 

 the natural resources of India. 



D' 



iR. E. H. HANKIN has made some interesting | 

 observations on the " flight " of flying-fishes I 

 (Proc. Zool. Soc. London, 1920, pp. 467-74. 2 figs.}. 

 He concludes that much depends on the atmospheric 

 conditions. On a very still evening in the Arabian , 

 Sea he noticed that the length of a glide after leaving j 

 the water was only about a metre, and the fishes i 

 NO. 2703, VOL. 107] 



Flight of Flying- fishes. 



showed much lateral instability. During the same 

 voyage, but in sunshine and with a light wind, the 

 longer flights attained to between 200 and 400 metres 

 in length. The pectoral fins are usually in the " flat " 

 position, i.e. extended in the horizontal plane. Some- 

 times the wings are slightly inclined upwards, with 

 the outer part of the fin at a higher level than its 



