REVIEW. 89 



in a circular mass which surrounded it. This at first loses its 

 circular form, and becomes elongated in the direction of the long 

 axis of the spore, so as to become of an elongated ovoid form, 

 the spore remaining at one pole. As the envelope increases in 

 length the spore becomes paler and smaller, breaks up into several 

 parts, and finally disappears altogether, as the accompanying 

 woodcuts show (fig. a was drawn by Koch, h by Cohn). Koch 

 has even been successful in getting a second generation of spore- 

 forming fibres. 



This section of the paper concludes with drawing attention to 

 the fact that these observations have not been made once, but 

 repeatedly, and that the author has had the benefit of Professor 

 Cohn^s examination of his specimens. The negative results to 

 which C. O. Harz appears to have come ('Allgem. Med. Central- 

 zeitung/ 1876, No. 33) have no value in the face of his, which 

 are positive. 



3. To know whether the presence of Bacillus anthracis fully 

 explains the occurrence of splenic fever, it is necessary to have 

 some further information about its life-history and the conditions 

 under which it survives the sufferer, of whose death it has been 

 the cause, in order to spread its disease still further. 



To see how long they could survive the effects of drying, Koch 

 tried the following experiments : — Blood or spleen from an in- 

 fected animal was dried in a shady place, exposed to the air ; 

 with this a mouse was injected, and the results watched under 

 the microscope. That which w^as dried in very thin layers lost 

 its infective power after twelve to thirty hours, and, at the same 

 time, its power of growing into elongated fibres, in the incubat- 

 ing apparatus. Thicker layers retained their powers for two or 

 three weeks, and some, still thicker, for four or five. After a 

 longer time they were never capable of producing the disease, 

 and it may be said that such substances, thus dried, are never able 

 to produce splenic fever, unless they are also able to produce 

 spores from the fibres ; and, inversely, as the conditions of suc- 

 cessful cultivation, Koch found that 35° was the best for their 

 development, the spores appearing after twenty hours; at 30° 

 they took thirty hours; at 18° to 20° two and a half to three 

 days ; below 18° the appearance of spores was exceptional ; and 

 below 12° the growth of fibres was never observed. On the 

 other hand, at 40° development of spores was rare, and appeared 

 to cease at 45°. 



As to the necessary conditions of air-supply, the following 

 results were obtained : — Bacilli were rubbed up with the blood, 

 aqueous or vitreous humour of an ox, and placed in a well- 

 corked glass. Very rapidly did there appear a powerful smell of 

 putrefaction; the Bacilli disappeared after twenty-four hours 



