ADDENDUM TO APPENDICES A AND B 623 



from the fact that Prowazek, using the highest microscopic 

 powers, has observed similar bodies occurring in infective 

 exudates and of sufficient minuteness to pass through a coarse 

 filter. Appearances have been seen in these particles which 

 suggest multiplication. This takes place not by a simple fission 

 as in the bacteria, but by the particle assuming a dumb-bell 

 shape, the two elements of which gradually recede from each 

 other until the fine thread connecting them snaps. This special 

 behaviour in division, taken along with the failure of attempts 

 at culture, has caused them to be put in a special group the 

 chlamydozoa. The view held is that they are the actual infective 

 agents. On gaining admission to the cells for which they have 

 an affinity, they originate a reaction whereby the protoplasm 

 forms round them a sheath or mantle (^A-a/Avs) , which accounts 

 for the gross appearances seen in, e.g., the epithelial cells in 

 smallpox and in those of the cornu Ammonis in rabies. In 

 these the parasite multiplies to produce such appearances as the 

 initial corpuscles of the Guarnieri bodies of the Heine Innenin 

 klusionen of Negri. It is obvious that at present no definite 

 position can be taken up regarding the cogency of these views. 



