182 MICKOBES, FERMENTS, AND MOULDS. 



while their seven children, who slept on the second 

 floor, escaped. Salisbury ascertained that there was 

 a fog every morning, rising from a reservoir which 

 had been recently made. This fog reached the house 

 and rose above the first floor, but not as high as the 

 windows of the second floor, and penetrated into the 

 parents' bed-chamber through the open window. This 

 vapour had the same smell as the marsh, which was 

 covered with fever algse (Palmella febrilis), and pro- 

 duced the same feverish dryness in the throat and 

 pharynx. The vapour dispersed soon after sunrise, 

 and before the children had left their chamber. 



Salisbury likewise ascertained the polymorphism 

 of Palmella febrilis, a polymorphism which is con- 

 firmed by the recent observations of the skilful 

 naturalist Zopf, and this fact explains the mode in 

 which an aquatic alga can live in the human blood, 

 in the form of Bacillus or Spirillum. 



Still more recently (1879), marsh fever, or malaria, 

 which is so common in Sicily and in the Roman 

 Campagna, have been studied from the same point 

 of view by Crudeli, Cuboni, Cecci, and others, who 

 ascribe the disease to a vegetable parasite which they 

 call Bacillus malarial. This bacillus is abundantly 

 found in the blood of patients during the period of 

 attack, while during the period of acme which ter- 

 minates each attack only spores are found. The same 

 microscopic organism is found in all the malarious 

 districts of the Eoman Campagna, and it can be 



