13
(c) Characters of Amœba.
Havi ng descri bed t he seasonal preval ence of amœbi c i nf ect i on i n dysent ery,
we proceed to consider the results of the investigation of the amœba found. The
amœba was studied in the stools and pus of liver abscesses, both fresh and stained.
F u r t h e r , a m œ b æ c u l t i v a t e d o n t h e a g a r o f M u s g r a v e a n d C l e g g f r o m t h o s e a n d
many other sources were carefully observed. We never were able to get the
a m œ b a t o g r o w a p a r t f r o m b a c t e r i a . W e o b t a i n e d " p u r e m i x e d g r o w t h s " ; i t
would appear that, on artificial media, so far, bacteria are essential for the deve
- l o p m e n t o f a m œb æ , b u t t h a t t h e y c a n d e v e l o p i n c e r t a i n c o n d i t i o n s a p a r t f r o m
bacteria is evidenced by their growth in the liver pus, which in most cases is quite
st eri l e. I t may be t hat cert ai n st rai ns of amœbæ can grow wi t hout bact eri a ;
if this could be demonstrated much light might be thrown or the etiology of liver
abscess. By growing amœbæ outside the body on artificial media a more com
-plete study of the various phases in their life cycle can be made. A portion of the
agar wi t h a c ul t ur e of amœbæ on i t was pl ac ed on a s l i de, c ov er ed wi t h a c ov er
gl ass and ri nged wi th vasel i ne ; and i n thi s way the amœbæ coul d be studi ed
under the microscope in the fresh state for prolonged periods. Also, impression
preparations were made from the agar culture, fixed wet in hot corrosive alcohol
s o l u t i o n o f S c h a u d i n n , a n d s t a i n e d b y t h e i r o n h æ m a t o x y l i n m e t h o d o f H e i d e n h a i n ;
others were stained by Giemsa, but the best results were obtained by the
iron hæmatoxylin method. Drawings, by means of a camera lucida, were made
of a number of the preparations, fresh and stained. During our investigation,
t h e t y p e o f a m œb a m e t w i t h a g r e e d v e r y c l o s e l y w i t h t h a t d e s c r i b e d b y N o c 1
in Cochin China, who worked out the life cycle in Mesnil's Laboratory at the
Pasteur Institute, Paris. From the alimentary tract of healthy men and certain
a n i m a l s , a m œb æ c a n b e c u l t i v a t e d w h i c h p r e s e n t c h a r a c t e r s a p p a r e n t l y s i m i l a r
to those obtained from the mucus of dysentery stools. Consequently, when
monkeys are used for experimental feeding with encysted amœbæ, as was done
by Musgrave and Clegg 2 and repeated by us, and symptoms of dysentery
s u p e r v e n e w i t h a mœb æ i n t h e s t o o l s , i t i s a ma t t e r o f d o u b t a s t o w h i c h a mœb a
caused the lesion, the one on which the monkey was fed or the amœba normally
present. These facts indicate that the problem of the relationship of the various
a m œ b æ t o d y s e n t e r y i s a d i f f i c u l t a n d c o m p l i c a t e d o n e .
In this enquiry we have studied, as carefully as possible, the morphology,
l i f e h i s t o r y , e t c . , o f t h e a mœb a c u l t i v a t e d f r o m d y s e n t e r y s t o o l s , l i v e r p u s , n o r ma l
men and animals as well as tap water. Certain minute details connected with the
uncl ear di vi si on and reproducti on have been l eft for further study. Meanti me
1A
n n a l d e L ' I n s t i t u t e P a s t e u r
, No. : 3, Mars 1999.
2Ibid.