January i i, 1906] 



NA TURE 



257 



of 1903, 1403 plaice were marked in this way, and of these 

 287, or 19 per cent., have been returned to the association. 

 The general facts regarding migrations brought out by 

 these experiments are these : — the smaller fishes do not 

 appear to migrate to any considerable extent, and the 

 larger the fish is the more extensive are its migrations. In 

 some cases the distance travelled has been very consider- 

 able ; thus one plaice is shown to have travelled a distance 

 of 175 miles in about six weeks, and another travelled 

 a distance of 210 sea-miles in eight months. The general 

 trend of the migrations has been in a southerly direction 

 during the winter and in a northerly one during the 

 summer. As a rule, the smaller fishes travel from the 

 shallow water " nurseries " to the deeper waters during 

 the earlier period of their life. 



A most attractive part of these migration experiments is 

 the question of the transplantation, on a commercial scale, 

 of fishes from overcrowded grounds to those grounds 

 where the conditions for favourable growth are present, 

 but where there is not already an abundant population 

 of the kind of fish in question. An interesting account of 

 such an experiment is given by Mr. Garstang. Although 

 the conditions of nutrition on the well known Dogger 

 Bank are apparently very favourable for plaice, yet, on 

 account of its comparatively isolated situation, this area 

 contains a population of plaice which is probably far below 

 that which it is able to support. Accordingly, more than 

 1000 small plaice were transplanted from certain in-shore 

 grounds to the Dogger Bank, and in the course of a year 

 more than 40 per cent, of these fishes were re-captured 

 from the Bank itself and the slopes around it. It is shown 

 that the growth-rate of these fishes was far in excess of 

 that of those living on the ordinary in-shore fishing grounds, 

 and the question of the practicability of the wholesale 

 transplantation of small plaice from the shallow-water fish- 

 ing grounds to such grounds as the Dogger Bank is care- 

 fully discussed. It is very questionable, however, whether 

 transplantation operations on such a scale could be 

 arranged at all so as to be successful. 



The remainder of the report deals with the records of 

 the fishing experiments and with various other matters. 

 Dr. Wallace presents a report on the growth-rate of the 

 plaice based on ' the examination of the annual growth- 

 rings in the otoliths. Mr. Todd contributes a lengthy 

 account of his examination of the contents of the stomachs 

 of a very great number of fishes caught in the course of 

 the trawling operations, and draws some interesting con- 

 clusions on the food of the various species dealt with. 

 Lastly, Mr. Gough reports on the occurrence and distribu- 

 tion of the plankton of the English Channel during 1903. 



The records of the trawling experiments contain a large 

 mass of observations which are capable of much further 

 analysis than has been attempted in the present report. 

 84,000 measurements of individual fishes have been made 

 in the North Sea and in in-shore waters, and when these 

 are considered along with the records of the hauls made 

 by the Scottish Fishery Board's exploring steamer abundant 

 material should be forthcoming for a discussion of the 

 distribution of fishes in the North Sea according to their 

 age and size. Altogether the North Sea Fisheries Investi- 

 gation Committee is to be congratulated on the publication 

 of these reports. J. Johnstone. 



INSECT PESTS OF THE COTTON PLANT. 1 

 ""THESE two reports may be taken as object-lessons of 

 the way in which such economic investigations should 

 be carried out by the agricultural departments of pro- 

 gressive countries. 



The wide area over which cotton cultivation is spreading 

 makes the investigation of its enemies in those regions 

 where it has long been cultivated of great value. Such 

 researches guide us in investigating new enemies, and they 

 prepare us to guard against the introduction of pests with 

 foreign seed. 



The authors of the report on the bollworm have pro- 



1 "The Cotton Bollworm." By A. L. Quaintance and C. T. Brues. 

 U.S. Department of Agriculture. Bureau of Entomology, Bull. 50. Pp. 

 155 + plates xxv+figs. 27. (1905.) 



"The Mexican Cotton Bill Weevil." By W. D. Hunter and W. E. 

 Hinds. Idem, Bull. 51.. Pp. 181 +plates xxiii+figs. 8. (1905) 



NO. T889, v OL. J3~] 



duced a work of great value to all cotton planters. The 

 pest i^ recorded from North and South America, the West 

 Indies, Europe, many parts of India, China, and Japan, 

 the East Indies, Australia and New Zealand, and even in 

 the Gilbert and Navigator Islands. Of particular interest 

 is the record from the Sudan and British East Africa, but 

 it is not recorded as attacking cotton there. Besides 

 infesting cotton, it is equally destructive to corn, and the 

 authors tabulate seventy other food plants, distributed 

 over twenty-one natural orders. 



There are excellent plates showing ova, larva; damaging 

 the buds, tassels and ears of sweet-corn as well as cotton. 



The injuries are explained, and it is clearly pointed out 

 how the cotton becomes infested bv the third and fourth 



Fig. 1.— Work of Bollworm in Cotton Bolls. 1, Bollworm eating into a 

 half-grown cotton boll ; 2, bollworm boring into a full-sized cotton boll ; 

 3, full-grown bollworm and its work in large cotton boll ; 4, cotton 

 boll only partially destroyed by bollworm, two "locks" open, the others 

 destroyed (original). 



generations of larva", the previous ones feeding upon the 

 corn. 



The summary given of the life-history shows that the 

 moth may lay from 500 to 3000 eggs, especially upon the 

 " silks " of corn and the '" squares " of cotton. During 

 warm weather they hatch in two or three days. In spring 

 the young larva? eat the buds, later the silks and tassels 

 oi ill' can: in August and September they attack the 

 cotton. They bore directly into the "squares" and 

 "bolls," and destroy the hitler. Maturity is reached in 

 two weeks; they then enter the soil to pupate. Detailed 

 descriptions are given of all the stages, the effects of 

 climate, and variations in colour. Nothing definite is 

 shown to account for the great variation seen in the larvae. 



