S GEORGE V SESSIONAL PAPER No. 38a A. 1918 



XIII. 



BACTERIAL DESTRUCTION OF COPEPODS OCCURRING IN MARINE 



PLANKTON. 



By Wilfrid Sadler, M.Sc, B.S.A., Bacteriological Labatories, Macdonald College 

 (McGill I^niversity), Province of Quebec, Canada. 



During the summer of 1916 I was investigating the bacteriological content of 

 " Swelled Canned Fish " for the Biological Board of Canada at the Marine Station, 

 St. Andrews, N.B. 



While there Dr. Arthur Willey (Professor of Zoology, McGill University) called 

 my attention to the condition of some of the copepods — (Calanns finmarcliicus — upon 

 which he was conducting researches. Under the microscope it was seen that many parts 

 of the tissue of copepods which had died in culture flasks were completely destroyed 

 by masses of what appeared to be bacteria. It was particularly noticed that the axial 

 cavity in the first antennae was entirely occupied by a dense column of writhing organ- 

 isms. Tubes of nutrient broth were inoculated direct from the copepods and after 

 two days' incubation at room temperature a definite clouding of the medium was 

 noted. 



At the request and on the suggestion of Dr. Willey I have proceeded with tlie 

 examination of the cultures secured, and have obtained in pure culture the organisms 

 concerned. Three specific strains of bacteria have been isolated. 



Inasmuch as the work may have some practical significance in relation to the 

 general subject of marine biology, and is of scientific interest, this report of the 

 detailed studies of these organisms has been prepared. 



MEDIA EMPLOYED. 



I beg-an by using various media prepared from fish concoctions in addition to the 

 ordinary laboratory media. The latter, however, proved to be more satisfactoiy in 

 every way and I have therefore confined myself to their use entirely. 



Beef Peptone Agar. — Standard methods ^ — Beef extract being substituted for 



meat. 

 Beef Peptone Gelatine. — Standard methods. ^ 

 Glucose Agar. — 1% glucose added to agar prepared as above, immediately before 



tubing. 



Sodium Indigo Sulphate Agar. — 3 per cent, sodium indigo sulphate with 2 per 

 cent, glucose added to neutral agar, tubed and sterilized in flowing stream for 

 three successive days. 



Tochtennanns Serum Agan. — - For digestion test. 



Ldefflers Blood Serum.— ^ " " " 



Aesculin Agar.'^ — For specific reaction of organisms of the colon-aerogenes group. 

 Loops of a broth culture spread on plates. 



Neutral Red Bile Salt Agar.° — Ditto, ditto. 



Bouillon for V oges-Proshauer reaction.^ — 



Bouillon for tlie Methyl Red Reaction."^ — 



Solution for reduction of Nitrates to Nitrites. — Giltay's synthetic solution was 



used, and also a peptone potassium-nitrate solution. 

 SSa— 15 217 



