1866 Journal of Applied Microscopy 



serting an infected needle into the body of the insect. In his experiments, which 

 number many hundreds, he used species of all order of insects, and found that 

 the bacteria would grow in insects from every order. The particular organism 

 of the ulcers, developing in the insect, produces the death of the animal in three 

 or four weeks. The body of the insect is then found to be filled with a practi- 

 cally pure culture of the organism. A long series of exeriments has convinced 

 the author that this method of using an insect as a culture medium is capable of 

 development and of much practical use to bacteriologists. h. w. c. 



Griffon, V. The Agglutination of Pneumococ- In order to investigate the serum re- 

 cus. These de Paris, looo-iooi. .. , ^ , 



^ action of pneumococcus we must have 



recourse to a special technique. One to 2 c. c. of serum should be inoculated with 

 the pneumococcus and the culture should at once be put into an incubator at 

 37 °C. for fifteen hours. When the human organism succumbs to an infection of 

 pneumococcus, the serum scarcely becomes cloudy, and a microscopical examina- 

 tion reveals somewhat isolated diplococci which are distributed uniformly over 

 the field, sometimes joined in little chains of from four to six members. 



In the case of pneumococcus infection the agglutination may be macroscopic 

 or microscopic. 



1. When the agglutination is macroscopic or " pronounced," the serum re- 

 mains clear and at the bottom of the tube may be seen a very distinct precipitate 

 which presents different aspects. It may have the form of a peculiar cup-shaped 

 buffy coating following the contour of the lower end of the tube ; or it may con- 

 sist of pseudo-membranous fragments which are multiple, flattened, or in rib- 

 bons ; of irregular flakes; or of very fine dust-like grains which are held in sus- 

 pension if the tube is shaken. These are the reactions which- may be observed 

 in the order of their decreasing intensity. 



2. When the agglutination is microscopic or "slight," the inoculated serum 

 will have lost its first clearness, and the cloudiness will be more or less marked. 

 With the microscope can be seen either chains, or masses, or a mixture of both. 

 From the edge of the masses chains may often be seen detaching themselves, 

 rolling up, and forming around the islet from which they emanate a kind of col- 

 lar, making it look like the head of a medusa. The chain is only the first step 

 in the agglutination. The phenomenon takes place as soon as the microscope 

 can be used and may become macroscopic after seven hours. 



A drop of the culture on serum may be spread out, dried, and stained with a 

 carbolated solution of methylen blue. In studying the pneumococcus serum re- 

 action it is not necessary to have the serum strictly aseptic because the sapro- 

 phytic germs of the skin do not develop rapidly enough to retard the reaction. 

 The serum should not be coagulated. The pure culture of pneumococcus may 

 be preserved in diluted blood or upon coagulated blood. Normal serum has no 

 reaction. It sometimes happens, but only rarely, that the serum of a pneumonia 

 patient will agglutinate only the pneumococcus of that same patient. 

 Tr. by Eleanor Larrabee Lattimore. A. GiRAULD. 



