1863.] 487 



instead of one. In the carp double and single projections occurred 

 in about equal proportions ; in the minnow double projections were 

 all but universal. The second projection was situated sometimes at 

 the opposite pole of the disk, sometimes in near proximity to its 

 fellow, or at any point between. Very rarely, a third projection was 

 seen in the dace. 



In the blood of the frog there was a strong tendency to the inde- 

 finite multiplication of the projections ; two, three, four, and even 

 five would rise in succession on the surface of the disk. It appeared, 

 too, not unfrequently as if the entire outer membrane of the cell was 

 detached from the parts beneath and raised into eight or ten unequal 

 elevations, giving the outline of the disk an irregularly crenate ap- 

 pearance*. 



The formation of these singular projections, or pullulations, on the 

 blood-disks could be watched, without difficulty by placing a drop of 

 the tannin-solution beneath the covering glass, and permitting a little 

 blood to insinuate itself into the solution under the microscope. As 

 the blood flowed in and mingled with the tannin, the corpuscles were 

 observed gradually to enlarge, and then suddenly, without previous 

 warning, to shoot out the projection. As a rule, it does not appear to 

 grow afterwards. The phenomenon was finely seen in the defibrin- 

 ated blood of the fowl after it had been allowed to sink through 

 a column of syrup (sp. gr. 1025) in a test-tube. Fowl's blood 

 washed in this way was mixed, in a little glass, with about five times 

 its volume of the tannin-solution, and a drop immediately put under 

 the microscope. The disks first enlarge and become rounded, and 

 the central nucleus comes into view. In thirty or forty seconds the 

 pullulation begins ; and each corpuscle, with instantaneous rapidity 

 and without previous sign, throws out its bud. The disk itself suf- 

 fers not the least disturbance during this act ; it preserves its sym- 

 metry unchanged, as if it had no concern, beyond that of proximity, 

 with the sudden apparition on its surface. 



No visible rupture of the cell-wall took place. The circular out- 



* There is a certain adjustment of the proportions between the tannin-solution 

 and blood required to bring out the effects described in this paper ; but the proper 

 proportions are, practically, very easily found after a few trials for each kind of 

 blood. In mammalian blood, one drop of blood mixed in a conical glass with 

 four or five of the solution generally answered perfectly. Any considerable excess 

 of blood or solution above these proportions caused destruction of the corpuscles. 



