142 



THE AMERICAN MONTHLY 



[August, 



particular organism would develope 

 in the blood of a yellow fever pa- 

 tient, enclosed in a culture-cell, 

 when proper precautions were taken 

 to prevent infection by atmospheric 

 germs. I may say here that my 

 results were negative, and that w^hile 

 " in certain specimens, kept under 

 observation in culture-cells, hypho- 

 mycetous fungi and spherical bac- 

 teria made their appearance, after 

 an interval of from one to seven 

 days. The appearance of these or- 

 ganisms was, however, exceptional, 

 and in several specimens, taken 

 from the same individual at the same 

 time, it occurred that in one or two 

 a certain fungus made its appear- 

 ance, and in others it did not." 

 {PreliTTh. Bep. of Havana Cora, to 

 Nat. Board of Health). The in- 

 ference being that, in those speci- 

 mens in which organisms were 

 found, infection by atmospheric 

 germs occurred during the brief 

 time occupied in collecting and 

 enclosing the drop of blood in 

 the culture-cell. 



In these and like experiments a 

 culture- cell is required which will 

 preserve the blood in a fluid condi- 

 tion, free from atmospheric conta- 

 mination, and yet surrounded by a 

 sufficient amount of air to furnish 

 the necessary oxygen to any orga- 

 nisms that may develope from 

 any germs that may be present 

 in the blood. In addition to this 

 it is necessary that a very thin 

 stratum of blood should be within 

 reach for examination by the high- 

 est power immersion objectives. 



The Boldeman cell (made by Mr. 

 Otto Boldeman, 150 W. 16th Street, 

 New^ York), fulfils the first require- 

 ment, and is a very useful cell for 

 many purposes. In this cell a cen- 

 tral eminence is surrounded by a 

 circular channel, ground in the 

 glass, which serves the purpose of 

 an air-chamber. The summit of 



the central eminence is slightly con- 

 cave and the drop of fluid to be 

 observed is placed upon this and 

 protected with a thin glass cover, 

 which is attached to the slide by a 

 circle of cement, or simply by a 

 little oil. 



The main objection to this cell, 

 for my purpose, was that the stratum 

 of blood held in the shallow cup of 

 the central eminence, was too thick 

 for satisfactory examination with 

 high powers ; that portion of the 

 fluid next the cover, which could be 

 brought into focus, being shut off 

 from the light by floating corpuscles 

 in the back-ground. 



This difliculty led me to invent 

 the culture-slide here described, 

 which, so far as I know, is new. 



A circular hole, about 34^ -inch in 

 diameter, is diilled through the 

 centre of a glass-slide. A very thin 

 circle of cement, ^-inch in diame- 

 ter, is then turned about this cen- 

 tral hole on one side of the slide, 

 and a thin glass cover is attached to 

 it by gentle ])ressure. 



When the cement is thoroughly 

 dry, the cell is ready to receive the 

 drop of blood or other fluid which 

 is to be observed. This is placed in 



Fig. 24. 

 the bottom of the cell (a. Fig. ^Jf) and 

 flows, by capillary attraction, into the 

 space below between the thin cover 

 and the slide until it extends to the 

 circle of cement by which the cover 

 is attached. We have thus a thin 

 stratum of the fluid, between the 

 points h and c, which may readily 

 be examined by inverting the slide 

 and bringing an immersion lens 

 down upon any point between the 

 central air-chamber and the circle of 

 cement by which the cover is at- 

 tached. Finally, the cell is closed 



