November 27, 1885.] 



SCIENCE. 



467 



St. Jerome's Creek from 1880 to 1885 ; while the 

 most conclusive and irrefragable evidence is that 

 obtained as the results of experiments instituted 

 by Professor Brooks and Messrs. Blackford and 

 Mather during the present year. 



The maximum efficiency of the cultch is not 

 reahzed in any of the old forms of collectors, for 

 the reason that the cultch cannot be kept clean ; 

 second, because both sides of the cultch cannot 

 be exposed to the passing fry ; third, because the 

 fry cannot be forced to pass over and amongst the 

 cultch repeatedly ; fourth, because the cultch has 

 hitherto been scattered over too great an area, and 

 throughout only two dimensions of a body of 

 \%'ater, namely, its horizontal extent, whereas it is 

 possible to do far more ; that is, to avail ourselves 

 of the possibility of obtaining spat throughout 

 the three dimensions of a body of water charged 

 with embryo oysters in the veliger condition. 

 These are good and sufficient reasons for my 

 assertion that cultch has hitherto been wastefuUy 

 and unscientffically appHed. 



The new method outlined above will be ex- 

 plained in detail, with plans drawn to scale, in an 

 extended illustrated article of mine now ready for 

 pubhcation by the U. S. fish commission. In fact, 

 as a result of scientific inquiry, it has come about 

 that there may be appUed a more effectual means 

 of diminishing the mortality and frightful waste 

 of oyster embryos, which occur under the stress 

 of those natural conditions which determine the 

 ' struggle for existence.' This result was predicted at 

 the close of a lecture dehvered in 1883 by Professor 

 Huxley, in these words : "I, for my part, believe 

 that the only hope for the oyster-consumer lies 

 first in oyster-culture, and, second, in discover- 

 ing a means of breeding oysters under such con- 

 ditions that the spat shall be safely deposited. 

 And I have no doubt that when those who under- 

 take the business are provided with a proper 

 knowledge of the conditions under which they 

 have to work, both these objects will be attained." 



John A. Ryder. 



PASTEUR AND HYDROPHOBIA. 



Pasteur's communication upon the treatment 

 of hydrophobia by inoculation, to which reference 

 was made in a recent number of Science (Nov. 6), 

 is fully and authoritatively reported in the 

 Comptes rendus of Oct. 26. His present results 

 are based upon a series of experiments upon rab- 

 bits and dogs, extending over a period of three 

 years. So numerous have been these experiments, 

 and so uniform and certain their results, that he 

 has no hesitation in applying these results to other 

 animals, including man. 



Pasteur finds, that if a rabbit be inoculated by 

 trepanning the skull, and placing beneath the dura 

 mater a bit of spinal cord from a dog which has 

 died of rabies of the streets (rage des rues), the 

 animal always develops hydrophobia after a 

 period of incubation of about fifteen days. If 

 from the spinal cord of this first rabbit a second 

 be inoculated in a similar way, and from the 

 second rabbit a third, and so on in regular 

 series, it is found that the period of incubation 

 becomes shorter and shorter, until, after the virus 

 has thus passed through forty to fifty rabbits, the 

 duration of incubation is reduced to seven days. 

 The incubation has remained at this poiat for a 

 series of ninety inoculations, and it shows no ten- 

 dency further to decrease. The virus has now 

 reached its highest degree of intensity, and it re- 

 mains of a constant quality. It is possible, there- 

 fore, to have such a pure virus of rabies at aU times 

 at disposal. 



If portions of the spinal cord of rabbits which 

 have died of this uitense rabies be cut out with 

 every precaution to prevent contamuiation, and if 

 these portions of cord be suspended in a dry at- 

 mosphere, the virulence of the poison progressively 

 disappears until it is completely extinguished. 

 The time required for the extinction of the virus 

 varies somewhat with the thickness of the cord, 

 but especially with the temperature. The lower 

 the external temperature, the longer the vu'us 

 lasts. To preserve the cords, Pasteur places them 

 in flasks, in Avhich the air is rendered dry by bits 

 of potash in the bottom of the flasks. It is possi- 

 ble, therefore, to have the virus of rabies in all 

 degrees of intensity. 



In order to render a dog refractory to hy- 

 drophobia, it is necessary to inoculate him with a 

 series of spmal cords from rabbits dead of rabies, 

 beginning with cords containing the weakest vii-us, 

 that is, the cords longest preserved, and ending 

 with cords containing the most intense vu'us, that 

 is, cords jDreserved only one or two days. The 

 animals are inoculated every day with cords 

 representing successively each day or each two days 

 of preservation. The inoculation is effected by 

 injecting beneath the skin a Pravaz syringeful of 

 sterilized bouillon in which a fragment of the 

 spinal cord has been rubbed up. In tliis way 

 complete immunity to the disease is established ; so 

 that, after the treatment is finished, the animal can 

 be inoculated either subcutaneously or beneath the 

 dura mater, with the most intense rabid virus, and 

 no symptoms of hydrophobia appear. Pasteiu- has 

 fifty dogs, of all ages and of all races, which in this 

 way, without a single failure, he has rendered re- 

 fractory to hydrophobia. The treatment is ef- 

 fectual even if it be apphed after the dog has been 



