1596 Journal of Applied Microscopy 



A catalogue of the Marine Invertebrata of Eastern Canada, by Dr. J. F. 

 Whiteaves, has been published by the Geological Survey of Canada (1901). It 

 consists of a systematic list of all the species described from the Bay of Fundy, 

 the Atlantic coast of Nova Scotia, the Gulf and Mouth of the St. Lawrence river 

 as far north as the straits of Belle Isle. The localities at which some of the 

 species are found fossil in the Pleistocene deposits are also briefly indicated. — 

 Nature, 64 : 1 666. 



Numerous inquiries have been received asking where and at what cost the 

 bulletin of photo-micrographs issued from the Biological Laboratory of Earlham 

 College, and noticed in our August number, may be secured. The bulletin is pub- 

 lished by Nicholson iv Bro. of Richmond, and may be had at twenty-five cents 

 per copy. 



QUESTION BOX. 



Inquiries will be printed in this department from any inquirer. 

 The replies will appear as received. 



REPLY TO QUESTION No. 13. 



A quantitative test for the bacteria in milk can be made with very low magni- 

 fying power. To do this a known quantity of milk is diluted with a known 

 quantity of sterilized water. This is evenly spread over a gelatine culture in a 

 Petri dish. Place this in a warm (not above 100°F) and dark place for thirty-six 

 hours, and it will then be ready for examination. The bacterial colonies, many 

 of which can be seen with the unaided eye, will show the approximate number of 

 bacteria present in the milk used. The Petri dish may be placed, without 

 uncovering, upon the stage of the microscope, and the colonies examined with 

 the low power. Objectives ranging from the 2-inch to the 73-inch may be used. 

 Directions for making the gelatine culture may be found in almost any work on 

 bacteriology, and Petri dishes can be purchased for twenty-five cents apiece. 



C. A. Whiting. 

 REPLY TO QUESTION No. 14. 



In response to the inquiry of your correspondent this month, allow me to say 

 that Tallqvist's method of haimoglobin estimation consists of specially prepared 

 paper upon which a drop of blood is allowed to fall, and a color scale for com- 

 parison. It is accurate to about ten per cent. It costs $1.25, and may be 

 obtained of the Harvard Cooperative Society, Boylston street, Boston. 



F. W. Hku-.ins, M. D. 



REPLY TO QUESTION No. 15. 



I have frequently transferred alcoholic specimens of animal tissue to formalin 

 without bad results. In fact, tissues originally placed in dilute alcohol are fre- 

 quently improved for histological purposes by being changed to formalin. 



C. A. Whiting. 



