PROTECTIVK INOCULATION. 



237 



den. After pa.ssage through a number of puinea pi^fi, a monkey was 

 infected with the strain by inhalation. The monkey died of pneumonic 

 plapfue, and a jjuinea pi^' was inoculated cutaneously with a portion of 

 the pneumonic lunj;: of the monkey. The culture sprayed was obtained 

 from the blood of this pfuinea p\f*. The f^rowth of two apar-slant-cultures 

 was suspended in about 40 cubic centimeters of normal saline solution 

 and about two-thirds of the suspension was sprayed into the cages as in 

 the precedinp,- experiment. The result was as follows: 



.Series II. — Infection by inhalation. 



Vaccinated eruinea piss. ■ 



Normal guinea pitra. b 



No. 5568 died in 4 days. 



No. 5617 died in 8 days. 



No. 5569 survived. 



No. 5618 died in 4 days. 



No. 5570 died in 4 days. 



No. 5619 died in 4 days. 



No. 5571 survived. 



No. 5620 died in 3 days. 



No. 5572 died in 3 days. 



No. 5621 died in 4 days. 



No. 5573 survived. 



No. 5622 died in 3 days. 



No. 5574 died in 10 days. 



No. 5623 died in 4 days. 



No. 5575 survived. 



No. 5624 died in 3 days. 



No. 5576 survived. 



No. 5625 died in 6 days. 



No. 5578 survived. 



No. 5626 died in 4 days. 



No. 5579 survived. 



No. 5627 died in 4 days. 



No. 5580 survived. 



No. ,5628 died in 3 days. 



No. 5581 survived. 



No. 5629 survived. 



No. 5582 survived. 



No. 5630 died in 3 days. . 



No. 5583 survived. 



No. 5631 died in 3 days. 



No. 5584 survived. 



No. 5632 died in 4 days. 



No. 5585 survived. 



No. 5633 died in 5 days. 



No. 5586 survived. 



No. 5634 died in 4 days. 



No. 5587 survived. 



No. 5635 died in 3 days. 



No. 5588 died in 7 days. 



No. 5636 died in 3 days. 



No. 5589 survived. 



No. 5637 died in 3 days. 



No. 5590 died in 5 days. 



No. 5638 died in 4 days. 



No. 5591 died in 7 days. 



No. 5639 died in 4 days. 





No. 5640 died in 3 days. 



" Total : 16 survived ; 7 died. 

 i> Total : 1 survived ; 23 died. 



Sixteen, or 69.6 per cent, of the vaccinated animals survived, 

 while all but one of the control ones (that is, 4.1 per cent) died 

 of plague infection. This one control animal probably screened 

 itself in some way behind the other guinea pigs and thus avoided 

 infection. 



Summary of all inhalation experim,ents upon guinea pigs. 



Guinea pigs. 



ToUl. 



Survived. 



Percent- 

 age of 

 survivals. 



Vaccinated 



34 

 36 



24 

 1 



70.6 

 2.8 



Normal 





