Determination of Carbon Dioxide in Cucumber Brines

A simple, accurate method for determining carbon dioxide in fermenting cucumber brines is described. The method involves distillation of carbon dioxide from the acidified brine into standardized sodium hydroxide inside a closed jar. The sample is injected by a syringe and needle through a rubber serum stopper placed in the jar cap, into an acid solution. A small vial of sodium hydroxide placed inside the jar traps the carbon dioxide as it distills from the acidified solution. After being held in the jar 24 hr at 37°C, the vial is removed; the remaining base is titrated to the phenolphthalein end point with standardized hydrochloric acid. Advantages of the method include a limited working time, minimized loss of carbon dioxide during analysis, and a relatively small sample size.

Parasitism of the European Pine Sawfly, Neodiprion sertifer (Geoff.) (Hymenoptera: Diprionidae), in Southwestern Ontario

Cocoons of Neodiprion sertifer (Geoff.) were collected in southwestern Ontario in 1941, 1943, 1946, 1947, and 1949 for experimental investigations at the Belleville laboratory. A total of 8,326 cocoons were collected, mainly within about eight miles northeast and east of Sarnia, Ont., but a few were collected at Strathroy and Brigden, Ont. Each cocoon was incubated separately in a small vial so that each parasite could be associated with the host cocoon from which it emerged. Sawflies emerged from 68 per cent of the cocoons and parasices from 12 per cent; dissection of the remaining cocoons showed 16 per cent contained dead sawfly larvae and pupae, and four per cent dead parasite larvae.