638 EXPEEIMENT STATION RECORD. 



younger growth and smaller branches of the trees on which the colonies occur 

 and then banding the trunks with tanglefoot. In this way a large part of the 

 ants was destroyed and practically all of the large fleshy pink scale on which 

 they feed. Though the remaining ants continued to live for a while on some of 

 the trees, they eventually disappeared from all of those treated. 



Monthly tappings are being made of 38 of the 10 to 11-year old Castilla 

 rubber trees which run from 24 J to 40 in. in girth at 3 ft. above the base. For 

 eight tappings the average yield per tree per tapping was a little less than 0.5 

 oz. of rubber. The quality of this rubber was pronounced as along with the 

 best and toughest Castilla rubber on the market. 



A study of the results of the manurial experiments with cacao conducted 

 at the botanic station, Dominica, H. A. Tempany (West Indian Bui., 14 

 (1914), ^(i- ~» PP- 81-119, pis. 6). — This comprises a review as a whole of ferti- 

 lizer experiments which have been conducted during the past 11 years and 

 have been noted from time to time (E. S. II., 30, p. 741). 



Analyses are given showing the composition of the soil of the cacao plats 

 in the original series, together with the effects of the various manurial appli- 

 cations on the composition of the soil. In respect to the nitrogen content the 

 soils of certain plats, notably those which have been mulched with grass and 

 leaves, show considerable accretions to the niti'ogen content which are unac- 

 counted for by the quantities of this constituent added in the manui'ial applica- 

 tions. It is suggested that these accretions are due to the action of free uiti'o- 

 geu-fixing bacteria of the Azotobacter type, since this type of organism was 

 found in the soils of each of the plats of the original series. 



Laboratory studies of changes occurring in these soils when kept in a 

 moistened condition showed that whereas the humus content of the soils tended 

 to diminish very rapidly the nitrogent content did not tend to fall off in the 

 same way as a rule, while an appreciable amount of nitrification always took 

 place. It is suggested that the ammonia formed in the early stages of ammo- 

 niflcation may function as a base to neutralize the nitric acid pi'oduced in the 

 latter stages of the process. 



The results of a study of the soil moisture conditions obtaining on each 

 of the plats show that none of the manurial treatments practiced has exerted 

 any appreciable direct effect on the moisture-retaining properties of the soil. 



An investigation was also made of the temperature of the soils of the plats 

 at different hours of the day and different seasons of the year. The results 

 show that when the plats are adequately shaded the soil temperature remains 

 very nearly constant at the value of the air temperature during the coolest por- 

 tions of the day. When adequate shading is absent, however, the soil tem- 

 pei-ature varies to a much greater extent. These results emphasize the utility 

 of shade in young cacao orchards. 



A record of the annual yields for each of the plats shows the beneficial 

 influence of various manurial applications. The largest increases were secured 

 by mulching and the next largest by complete manuring. A survey of the fer- 

 tilizer data for the whole period indicates that under the conditions of the ex- 

 periment it takes from three to five years for the trees to indicate differences 

 derived from various forms of treatment. 



In the concluding portion of the paper the relations between the annual 

 rainfall and the yields of cacao are considered and analytical information re- 

 garding the manurial constitution of various materials used for mulching is ap- 

 pended. 



Robusta cofifee (O Caf^ Robiista. Sao Paulo. Brazil: fe'ec. Agr.. Com., e Obras 

 Pub., 1913, pp. 59, pis. 5). — This comprises various reports presented to th^ 



