DEPARTMENT OF MARINE BIOLOGY. I39 



A detailed account of this apparatus, which would be out of place in this 

 report, will be published with full diagrams in vol. ix. No. 4 of the Journal 

 of the Marine Biological Association of the United Kingdom, by Mr. D. J. 

 Matthews. 



For taking soundings and obtaining bottom samples one of the "snapper- 

 rods," disengaging a 30-pound weight, as made by the Telegraph Construc- 

 tion and Maintenance Co., of London, was used in conjunction with a 

 spring-balance which indicated the decrease in tension of the wire on disen- 

 gaging the weight. 



The temperature at the depth at which the samples were taken was recorded 

 by reversing thermometers made by Messrs. Negretti & Zambra, of London. 

 These thermometers were tested and corrected by the National Physical 

 Laboratory at Teddington, England. They were provided with auxiliary 

 thermometers sealed within the same outer glass tube as the reverser, so 

 that the correction that it is necessary to make for the difference in the tem- 

 perature at which the reversal took place and that at which the thermometer 

 is read could be easily applied. The volume of the upper bulb of the re- 

 verser, expressed in degrees of the stem at 0° C. (Vo), was engraved on 

 the back of the stem of each reverser, so that all the data were at hand for 



. . J • , 1. r , (t — f)(Vo-j-t) 



makmg the correction m accordance with the formula 7 



6,300 



where t = the temperature recorded by the reverser and t' = the tempera- 

 ture shown by the auxiliary thermometer at the time of reading. 



The mechanism by which the thermometer frames were reversed was part 

 of the water-bottle apparatus. 



The chief culture media employed were the following : 



I. Peptone Agar: 



Peptone (Witte's) 2.0 grams. Remarks: This medium was used 



Potassium nitrate (KNO3). 0.5 gram. in the routine plating of the 



Sea-water 1,000.0 c. c. samples, for making counts. It 



Agar agar 18.0 grams. solidifies at about 38° C. 



II. Gran's Medium: 



Potassium nitrate (KNO3). 0.5 gram. Calcium malate is only slightly 



Sodium phosphate (Nas- soluble in water (about i/20th 



HPOi, 12H2O) 0.25 gram. per cent), and so can be added 



Calcium malate (CjHsCOH) in excess. 



<^PQQ>'Ca) ...about. 5.0 grams. 



Sea-water 1,000.0 c. c. 



III. Potassium Malate Agar: 



Potassium malate (C2H3- This medium was only filtered 



/'nw^ ^COOK ^„ „„^ through glass wool, so that a 



^'^"^"-COOK) ^-^ ^^^^- very slight precipitate of cal- 



Sodium phosphate (Na2- cium phosphate was retained. 



HPO4, 12H2O) 0.25 gram. 



Potassium nitrate (KNOa)- 0-5 gram. 



Agar agar 18.0 grams. 



Sea- water 1,000.0 c. c. 



IV. Calcium Succinate Medium: 



Calcium succinate (C2H<- This medium was boiled and fil- 



<C00^^ tered to remove the slight pre- 



COO - ^^ --^ gi'a"^s. cipitate of calcium phosphate 



Potassium nitrate (KNO3). 0.5 gram. before sterilization; with the 



Sodium phosphate (Na2- addition of phosphate it gave a 



HPO4, 12H2O) 0.25 gram. more vigorous growth than if 



Sea-water 1,000.0 c. c. omitted. 



