August 24, 18n?.] 



SCIENCE. 



21:3 



separated b\- gravitation is equally linnnless. 

 Taking up the study liere, I have proved that 

 the exact degree of heat wliich, in a given time, 

 kills the micrococcus {132" K. for lo minutes), 

 destroys the virulence at precisely the same 

 point ; also that the proportion of carbolic acid, 

 of sulphuric acid, and of a solution of chlo- 

 rides (Piatt's), which destroys the virulence 

 in from two to four hours, corresiwnds with 

 the proportion which is required to kill the 

 organism in the same time. 



The effect of heat and of these disinfect- 

 ants on the virus was determined bv inocula- 

 tion experiments. The point at which the 

 micrococcus is killed was learned by placing a 

 drop or two of virus in the sterilized liquid of 

 a cultivation-tube after the proper proportion 

 of disinfectant had been added. In a given 

 lime a drop was taken from this tube, and 

 placed in a second one which contained a 

 favorable medium for the growth of the germs. 

 If the schizophj'tes had been destroyed by the 

 disinfectant, there would be no multiplication ; 

 while, if the3- had resisted it, they would cer- 

 tainly reveal the fact by developing in their 

 usual manner. The exact correspondence 

 which exists between the results of the two 

 series of experiments in everj- case, is also an 

 evidence of the reliability of the method. 



While it might be conceived, that, even 

 though the virulent agent consisted of some- 

 thing entirely different from the micrococcus, 

 both might be destroyed by the same degree 

 of heat in the same time, it is not conceiv- 

 able that this would also occur from the effect 

 of three different chemical agents. If it were 

 necessary, this line of evidence could probably 

 be increased indefinitely ; but it is already 

 equal to what is usually' considered necessary 

 to demonstrate a point in other departments of 

 science. 



It is possible, then, by present methods of 

 research, to determine satisfactorih" whether a 

 given organism is the cause of a certain dis- 

 ease, or whether it is an epi-plienomenon ; 

 and, if there is still much doubt in regard to 

 some of these, It would seem to be owing to 

 the fact that observers have relied too im- 

 plicitly upon the microscope, and neglected the 

 cultivation and inoculation experiments, that 

 are essential to definite and reliable conclu- 

 sions. D. E. Salmon. 



SPONGE-CULTURE IN FLOIUDA. 



The U. S. national museum has lately re- 

 (!ei\ed froui Messrs. McKesson and Robbins, 



sponge-importers of New York, an interesting 

 contribution representing the first successful 

 attem|)ls at sponge-cullivation on the Ameri- 

 can coast. It consists of only four specimens, 

 all of the finest or sheep's-wool variety, which 

 were raised from cuttings at Key West. Fla., 

 by the agent of Die above-named firm. The 

 localities in which the sponges were jjlanted 

 were not the most favorable for s|)onge-devel- 

 oi)nient, and their growth was therefore less 

 rapid and perfect than might otherwise have 

 been the case. They were fastened to the 

 bottom, in a depth of two feet and a half, 

 by means of wires or sticks running through 

 them, and allowed to remain down a period of 

 about six months before they were taken up. 

 Fully four months elapsed before they recov- 

 ered from the injury done them in the cutting, 

 which removes the outer ' skin ' along the 

 edges of the section ; and the .actual growth 

 exhibited was for about two months only. 

 The original height of each of the cuttings 

 was about two inches and a half. One was 

 planted in a cove or bight where there was 

 little or no current, and its increase in size 

 was very slight. The other specimens were 

 placed in tide-ways, and have grown to from 

 four to six times their former bulk, which 

 certainly promises well for the future of 

 sponge-pro|):igation. Two hundred and six- 

 teen specimens in all were planted at the same 

 date, and, at the last accounts, those which 

 remained were doing finely. 



The chief obstacle to the artificial cultiva- 

 tion of sponges at Key West arises from the 

 fact that the sponge-fishermen infest everv 

 part of the region where sponges are likely to 

 grow, and there is no legal protection for the 

 would-be culturist against intruders. The 

 enactment of judicious laws bearing upon this 

 subject by the state of Florida, or the grant- 

 ing of special privileges confeniiig the right 

 to occupy certain prescribed areas for sponge- 

 propagation, would undoubtedly tend to in- 

 crease the annual production of "this important 

 fishery, which has remained at a standstill for 

 several years past, mainly because of the 

 partial exhaustion of several of the most ex- 

 tensive sponging-areas. 



Accompanying tliese artificial growths was 

 a collection of over a hundred speijimens of 

 the various grades of Florida sponges of 

 different sizes, each labelled with its supposed 

 age, l)ased upon estimates of the average rate 

 of growth, by the sponge-collectors. This 

 entire collection now forms a part of the 

 American exhibit at the great London fisheries 

 exhibition. R. Rathblx. 



