582 EXPERIMENT STATION RECORD. 



"At the beginning of the test the tick-free and ticli-infested groups gave 

 practically the same amounts of milk; at the close the tick-infested gave only 

 65.8 per cent as much as the tick-free. The tick-free group gained 6.1 per 

 cent in body weight ; the tick-infested 3.6 per cent. 



" Spraying or dipping tick-free cattle in an ar.senical solution causes a 

 marked though temporary decrease in milk flow. In this experiment there 

 was an average reduction of 6.1 per cent from the normal milk flow for a 

 period of five days following each of the four applications of the arsenical 

 solution. 



" Resistance of cattle to infestation by the tick is a variable quality. Of 

 the ten animals in the tick-infe-sted group, four became grossly infested ; two 

 more so than the average, and the remaining four but lightly infested. 



" The death of cow 15, due to excessive tick infestation, and various recur- 

 rences of fever in the other animals, emphasizes the extreme hazard of cattle 

 being continuously subjected to these losses by the tick. Cow 15 was one of 

 the best of the tick-infested group and represented at least a 10 per cent 

 loss from the capital invested in tick-infested cows. Furthermore, the losses 

 observed In this experiment were sustained on rations sufHcient to main- 

 tain body weights. It is thought that had there been but a scant supply of 

 food, as sometimes occurs when cows are on pasture, the tick-infested cattle 

 would have suffere<l earlier and probably to a greater degree than they did. 

 The losses in this case were in spite of a good maintenance ration. It is prob- 

 able that much of the spring losses in cattle now laid to starvation, due to 

 lack of pasturage, is materially aided by blood depletion due to ticks, and that 

 repeated dippings would save many cattle otherwise lost. 



" These experiments are not extensive enought to furnish an exact measure 

 of the amount of decrease in milk flow due to infestation, but they show that 

 the losses are considerable and vary in immune cows largely in proportion 

 to the extent of infestation, since in all cases the milk flow decreased faster in 

 the heavily infested than in the lightly infested cows. This is additional evi- 

 dence that the tick is a great hindrance to profitable dairying in the South. Even 

 in so-called inmume cattle, ticks cause irritation of the skin and withdraw 

 blood that otherwise would produce milk or meat." 



The dairy records of the experimental cows are given in tabular form in an 

 appendix. 



Investigations in regard to the action of immune sera against calf dysen- 

 tery (scours) in infections with the bacteria of the coli and aerogenes group, 

 O. Stenstrom {Svensk Vet. Tidskr., 18 (1913), No. 8, pp. 73-83; abs. in Centbl. 

 Bakt. [e/c], 1. Abt., Ref., 59 [1913), No. 7, p. 216).— This is a study of the 

 C. O. Jensen anticoli serum. The serum was able to fix complement. When 

 saturated with antigen and then centrifuged for the purpose of removing the 

 antigen the immunizing powers of the serum for guinea pigs were only slightly 

 reduced. Bacteria killed with toluol and suspended in sterile distilled water 

 were fatal for guinea pigs (endotoxic action). The toxic action was prevented 

 by immune serum but not according to the law of multiples. The serum 

 therefore apparently contains antitoxins, but its action is not entirely anti- 

 toxic. Leucocytes from exudates also acted antitoxic. In dilute solutions the 

 serum predisposes toward phagocytic action. Antiaggressins were detected iu 

 the animal exi^eriments. and the chief value of the serum is dependent upon 

 the presence of these substances. 



Studies on the hematology of normal and cholera infected hogs, R. R. 

 DiNwiDDiE (Arkansas Sta. Bui. 120 (19U), pp. 21-1,1, figs. S).— In the course 

 of a somewhat prolonged study of the blood of normal pigs and that of pigs 



