-^ 



.Y. / TURE 



[January i i, 1906 



mentioned a Chrysopa 

 larvse. Wasps appear 



ites are also described ; 



small hymenopteron, 



e ; hut from what we 



Fig. 2.— Various Results of Larval Work. 24, Leaf fed on extensively by 

 weevils in confinement ; 25, full-grown larva in square ready to bloom ; 

 26, full-grown larva in square of usual size ; 27, larva full-grown, ovary 

 in square entirely destroyed : 28, larva full grown, ovary untouched — 

 all reduced (original). 



gather from the report man cannot expect much help from 



these "natural clicks. " Re lial and preventive cultural 



measures are thus fully explained. 



The Mexican cotton boll weevil is luckily confined to 

 the United States, Mexico, < uba, and Guatemala. The 

 authors have been unable to verify the reports that il has 

 been found in Africa or Brazil, il a cotton weevil occurs 

 in the former country it is probably another species, as we 

 see is the case in the Philippine Islands. 



The Mexican weevil has the unique record of develop- 

 ing in less than twenty years from an obscure specie: into 

 a great pest. The authors ably describe its life-history 

 and destructive habits in Texas and elsewhere. In the 

 summary ol the life-history it is stated that the egg is 

 deposited by the female in a cavity formed by eating into 

 a square or boll. The egg hatches in a few days, and 

 the footless grub begins to feed, making a larger chamber 

 for itself as il grows. The pupa also occurs in the boll. 

 It is importanl to note that no other food than cotton lias 

 been found. 



Some interesting experiments are recorded which tend 

 to show that the weevils are not able to locate their food 

 by smell. 



Anothei eries oi experiments showed that the weevils 



prefer Egyptian cotton (Mit Alifi) to the American upland 

 cotton. 



Their capacity for reproduction seems appalling, judging 

 from the table given showing the annual progeny of one 

 pair of hibernating weevils, which amounts to 12,755,100! 



The beetles hibernate in many places, as in infected 

 bolls and stalks, and it is shown that the early destruction 

 of the stalks in the fall is the most effective way to reduce 

 the pest. 



Dissemination takes place in cotton in bales and that 

 sent for "ginning." Shipments of seeds are said to be 

 almost certain to carry weevils if coming from infested 

 areas. The report also shows another important point, 

 namely, that the pilosity of the plant affects the progress 

 of the weevil. Parasites do not seem to be of much use. 

 Doubt is cast by the authors upon the benefit ..I Pedi- 

 culoides ventricosus. Mention is also made of the possible 

 use of the Mexican ants (Ectotomma tuberculata), &c. 

 Of great importance to those who import seed is the result 

 showing that bisulphide of carbon is the best substance 

 to clean the seed. Fred. V. Theobald. 



THE GREAT GNOMON OF FLORENCE 

 CATHEDRAL. 

 A LTHOUGH numerous Christian churches are either 

 oriented or adorned with reference to some astro- 

 nomical phenomenon, there are few of such direct interest 

 to the astronomer as the magnificent cathedral of Florence, 

 which contains a gigantic contrivance for determining the 

 advent of the summer solstice. We refer to the famous 

 gnomon, placed in the dome of that cathedral by Paolo 

 Toscanelli about the middle of the fifteenth century, and 



described and illustrated by Mr. W. A. Parr in the 

 December number of Knowledge and Scientific News. 



Lalande in 1765 referred to this instrument as " la 

 meridienne que 1'on voit dans la Cathedrale de Florence 

 est le plus grand monument dAstronomie qu'il y ait au 



NO- I! 



VOL. 73 



