1874.] On the Circulation of the Blood. 291 



,of this fact seem possible either germs preexisting in them have sur- 

 vived the heat, or the organisms have arisen in them abiogenically, 

 These alternatives were subjected to two series of test experiments. In 

 the first series it was proved directly that there exist in ordinary air and 

 water particles which preserve their germinal activity after being boiled 

 for five minutes in previously sterilized liquids. The second series of 

 experiments showed that, in the extraordinary increase of resistance to 

 sterilization by heat exhibited by alkalized hay-inf usion, the action of the 

 alkali is to heighten the surviving power of preexisting germs, and not 

 to exalt the abiogenic aptitude of the infusion itself. 



The issue of the whole inquiry has been to fully confirm the main 

 propositions of the panspermic theory, and to establish the conclusion 

 that Bacteria and Torulce, when they do not proceed from visible parents 

 like themselves, originate from invisible germs floating in the surrounding 

 aerial and aqueous media. 



Nevertheless the author is unable to withstand the impression that this 

 general and common mode of origin is possibly supplemented, under 

 rare conditions, by another and an abiogenic mode of origin. The facts 

 on which this impression rests are comparatively few. They consist in 

 certain instances of greatly retarded germination of Bacteria in liquids 

 which had been exposed to a boiling heat, and in two very remarkable 

 instances of the growth of fungoid vegetations (not identical with those 

 usually developed after air infection) in plugged bulbs which had been 

 boiled in a can of water. 



If it should be hereafter established that Bacteria and fungoid vege- 

 tations do, under exceptional circumstances, arise abiogenically, this would 

 not overturn the panspermic theory, it would merely limit the univer- 

 sality of its application. 



April 23, 1874. 

 JOSEPH DALTON HOOKER, C.B., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered for 

 them. 

 The following Papers were read : 



I. " On some Points connected with the Circulation of the 



I 



Blood, arrived at from a study of the Sphygmograph-Trace." 

 By A. H. GARROD, B.A., Fellow of St. John's College, Cam- 

 bridge ; Prosector to the Zoological Society. Communicated 

 by Prof. A. B. GARROD, M.D., F.R.S. Received March 12, 

 1874. 



(Abstract.) 



The author commences by giving a table containing a fresh series of 



