1881.] NATURAL SCIENCES OF PHILADELPniA. 435 



the mercy of the breeze, although some observations seemed to 

 indicate a limited control of the thread by manipulation. 



He added that on previous occasions he had actually observed 

 the laying in, by air currents, of lines which were immediately used 

 for foundations. The above studies had been undertaken simpl}^ 

 to verify such studies, and because he had retained but the briefest 

 notes of former observations. While this use of air currents is 

 certainly placed beyond doubt, it is as certainly not the only 

 mode of laying foundation lines, and is dependent very much upon 

 the site chosen, the condition of the wind, the abundance of ])rey, 

 etc. Webs built in large open spaces are perhaps always laid out 

 by bridge-lines. In more contracted sites, the frame-lines are 

 generally carried around, and often a foundation is the result of 

 both methods.^ 



October 11. 

 The President, Dr. Ruschenberger, in the chair. 

 Three hundred and sixty-four persons present. 



On the Nature of the Diplifheritic Gontagium. — Dr. H. C. Wood 

 stated that the researches which formed the basis of his remarks 

 had been made under the auspices, and. indeed, at the suggestion of 

 the National Board of Healtli, by Dr. Henry F. Formad and 

 himself, who were jointly responsible for the facts and inductions 

 and jointly desei'ving of whatever reprobation or approbation 

 might be due. The full text of the work is now in the hands of 

 the National Board, and will be shortly published by them. 



In the spring of 1880 work was begun by inoculating rabbits 

 with diptheritic membrane taken from the throats of patients at 

 Philadelphia. It was found that only in a very few cases was anj^- 

 thing like diphtheria produced m the rabbit by inoculating with 

 the membrane. The inoculations were practiced by putting 

 pieces of the material sometimes under the skin, sometimes deep 

 in the muscles. Man}' rabbits died after some weeks, not of 

 diphtheria, but of tuberculosis. In a series of experiments it was 

 shown that this tuberculosis was an indirect and not a direct 

 result of the inoculation, and that any apparent I'elati on between 

 the two diseases is only apparent, not real. Next, the tracheas of 

 a series of rabbits were opened and false membrane inserted. It 



1 Since these notes were communicated, a copy of Nature (Sept. 23, 1881 ) 

 lias been received, in which it is said that Mr. Cambridge in the second 

 volume of his Spiders of Dorset modifies the opinion above quoted con- 

 cerning the influence of air currents. I have not yet received that volume 

 but make this statement on the authority of the journal referred to. — 

 H. C. McC. 



