191T] ECONOMIC ZOOLOGY ENTOMOLOGY, 759 



The growth of insect blood cells in vitro, R. W. Gla.ser {Psyche, S4 (1917), 

 No. 1, pp. 1-7, pi. 1). — This is a report of observations on the morphology and 

 behavior of srowing insect blood cells, made during the course of a study of the 

 pathological changes which take place in insect tissue, in which the tissue was 

 cultivated in vitro. 



Toxic values and killing eflS.ciency of the arsenates, A. L. Lovett and R. H. 

 Robinson (U. S. Dept. Agr., Jour. Agr. Research, 10 (1917), No. 4, pp. 199- 

 207). — This is a report of work carried on at the Oregon Experiment Station 

 in continuation of that of Tartar and Wilson previously noted (E. S. R., 34, p. 

 548). The results afford furtlier verification of the earlier work and give mate- 

 rial data on (1) the comparative time and (2) the approximate amount of lead 

 hydrogen arsenate and basic lead arsenate required to kill small caterpillars and 

 nearly mature caterpillars; and (3) the proportion of these arsenates devoured 

 by the small and mature caterpillars that passes through the alimentary canal 

 of the larvae. The work has been summarized by the author as follows : 



" Lead hydrogen arsenate has a higher killing efficiency at a given dilution 

 than either calcium or basic lead arsenate. It requires a longer period of time 

 to kill the nearly mature caterpillars than the small forms. All of the arsenic 

 devoured by the insects in feeding upon sprayed foliage is not assimilated, but a 

 portion passes through the intestinal tract in the excrement. The percentage 

 amount of the arsenic assimilated depends upon the arsenate used ; lead hydro- 

 gen arsenate was assimilated readily and most of the arsenic was retained in the 

 tissue, while much of the basic lead arsenate was found in the excrement. It 

 requires approximately 0.1595 mg. of arsenic pentoxid to kill 1,000 small tent 

 caterpillars and approximately 1.84 mg. of arsenic pentoxid to kill 1,000 nearly 

 mature tent caterpillars, irrespective of the particular arsenate used as a spray. 



" Preliminary experiments on the burning effects of calcium arsenate indicate 

 too severe injury to warrant the practical use of this spray." 



Winter cover washes, A. H. Lees {A7in. Appl. Biol., 2 (1916), No. 4, pp. 2^5- 

 250). — In continuation of work previously noted (E. S. R., 34, p. 253), it was 

 found that the best cover wash consists of lime 30 lbs., glue 2 lbs., potassium 

 dichromate | oz., and water 10 gal. " This lime-glue-dichromate mixture has 

 been tried against ordinary lime wash at Long Ashton and has given decidedly 

 superior results. An application to an apple tree stopped aphis hatching to 

 such an extent that hardly an aphis was to be seen on it throughout the season 

 though control trees were very badly attacked. The tree stood out all the 

 season from its fellows by the healthy green uncurled leaves and at the end of 

 the season by its very numerous well-developed fi-uit buds." 



Accessory wetting substances with special reference to paraffin emulsions, 

 A. H. Lees (Ann. Appl. Biol., S (1917), No. 4, pp. I4I-I49, fig. i).— -This discus- 

 sion is accompanied by a table which gives the results of tests of the wetting 

 power of paraffin emulsions and of other auxiliary wetting agents on certain 

 natural surfaces. 



The author concludes that there is no object in introducing greater quan- 

 tities of paraffin or soap since a 2 per cent soap-paraffin emulsion (20 lbs. soap 

 and 2 gal. of paraffin to 100 gal. water) gives perfect wetting. The work has 

 shown that it Is not possible to reduce the quantity of either the paraffin or 

 soap without destroying the desirable qualities of the mixture, and that the 

 above mentioned mixture is the cheapest that can be used which at the same 

 time has the highest wetting power. 



" The value of this 2 per cent emulsion lies not so much in its own killing 

 power as in the fact that it can act as a carrier, so to speak, for other fungicidal 

 or insecticidal bodies which, used alone, would prove them.selves insufficient to 



