N. MATERIA MEDICA, THERAPEUTICS, AND HYGIENE. 591 



Liebreich, is not so good as that from the left, because the 

 shadow falls upon the part of the paper to which we are 

 looking Light from behind is still worse, because the head 

 and upper part of the body throw a shadow upon the book ; 

 but the lio-ht that comes from the front, and falls on the face, 

 is by far the worst of all. 



A similar principle should be adopted in regard to the use 

 of artificial light, Naked gas jets Dr. Liebreich considers to 

 be injurious because of their unsteadiness, and he recom- 

 mends that glass cylinders be used with them ; and reflect- 

 ors are still better. Ground-glass globes ought not to be 

 used. These are useful for the ordinary lighting-up of a 

 room, as they diffuse the light more equally throughout all 

 parts, but for that very reason they give an indistinct light 

 for work, and, if they are opposite the eye, are dazzling and 

 injurious. Ground-glass, for the same reason, is objection- 

 able for lighting rooms, and should only be used for sky- 

 lights or the upper portion of windows. 



The arrangement of seats in drawing-schools should differ 

 from that in ordinary class-rooms by having a diagonal ar- 

 rangement ; or if the room be long and very narrow, and the 

 pupils only draw from copies, while the light comes from the 

 top, it will be best to turn the back to the light. 3 A, July 

 27,1872,49. 



PHYSIOLOGY OF VIRUS. 



Professor Chauveau has lately published an elaborate me- 

 moir upon the general physiology of virus, and sums up his 

 inquiries with the following propositions : First, healthy or 

 non-putrid pus has the power of producing inflammation in 

 any conjunctive tissue with which it is brought in contact; 

 second, this power belongs exclusively to the solid particles 

 held in suspension in the serum, the latter, at least, not con- 

 taining morbific elements of positive activity; third, the in- 

 flammation produced in the conjunctive tissue by these solid 

 particles is not the result of mechanical irritation, but is 

 brought about by means of a specially irritating power in- 

 herent in them ; fourth, the activity of this property depends 

 upon the intensity of the inflammatory process which has 

 produced the matter experimented upon ; very intense or 

 moderately acute, with corresponding phlegmons, it becomes 



