146 An Account of certain Organisms 



and become lost among the blood-corpuscles. The process reaches 

 its height within 2| hours, and from this time begins almost imper- 

 ceptibly to decHne ; the area about the mass is less densely occu- 

 pied by the moving forms, and by degrees becomes clearer, till at 

 last, after six or seven hours (often less), scarcely an element is to 

 be seen in the field, and a granular body, in which a few corpuscles 

 yet exist, is all that remains of the mass. The above represents 

 a typical development from a large mass in serum, such as that seen 

 in Fig. 3.* 



We have next to study more in detail the process of development 

 and the resulting forms. Commonly, the first appearance of activity 

 is displayed by the small free corpuscles at the margins, which, 

 previously quiescent, begin a species of jerky irregular movement, 

 at one time with 'their pale disk-surfaces uppermost, at another 

 presenting their dark linear profiles (Fig. 5, a and h). Not 

 unfrequently some of these are seen with a larger or smaller 

 segment of their circumference thicker and darker than the other 

 (Fig. 5,c). 



Earhest, and perhaps the most plentiful, of the forms are those 

 of a spermatozoon-like shape (Fig. 5, d), attached to the mass 

 either by the head or tail ; while, simultaneously, long bow-shaped 

 filaments appear (Fig. 5, e), having an enlargement in the centre. 

 Straight hair-hke filaments (Fig. 5, /) may also be seen, but they 

 are not very numerous. The time which elapses before they begin 

 the wavy movement is very variable, as is also the time when they 

 break away after once beginning it. Filaments may be seen per- 

 fectly quiescent for more than half an hour before they move, and 

 others may be observed quite as long in motion before they succeed 

 in breaking away from the mass. Commonly it is in the smaller 

 masses, and where the development is feeble, that filaments remain 

 for any time adherent. The spermatozoon-like forms appear, at the 

 head, on one view flattened and pale, on the other dark and linear 

 (Fig. 5, d) ; consequently the head is discoid, not spheroidal. The 

 bow-shaped filaments also present a dark straight aspect when they 

 turn over (Fig. 5, e), and are by far the longest of the forms, some 

 measuring as much as ^ioth of an inch. Many intermediate forms 

 between the round discoid corpuscles and those with long tails are 

 met with in the field, and are figured at Fig. 5, g. 



Small rod-shaped forms are very numerous, most of which, 

 however, on one aspect look corpuscular ; but in others this cannot 

 be detected, or only with the greatest difficulty ; slight enlarge- 

 ments at each end may also be seen occasionally in these forms 

 (Fig. 5, h). 



Usually late to appear, and more often seen in the profuse 



* The mass from wliich this sketch was taken was seen in full development 

 by several of the foreign visitors to the British Medical Association last year. 



