166 The Influence of Mass on the Production of Infusoria. 



THE INFLUENCE OF MASS ON THE PKODUCTION 

 OF INFUSOKXA. 



BY HENRY JAMES SLACK, F.G.S. 



In the account given, of M. Pouchet's experiments on the 

 production of infusoria, in the Intellectual Observer, vol. i. 

 page 88, reference is niade to his theory of the influence of the 

 mass of fermenting matter on the character and number of the 

 minute beings whose appearance is observed. If your readers will 

 turn to the article alluded to {" Conditions of Infusorial Life,") 

 they will find ample details of ,M. Pouchet's investigations, but 

 it will be well to cite his exact words on the particular subject 

 of these remarks. He says, " it is evident from this experi- 

 ment (one mentioned in an article), and from many others 

 which we have made of the same kind, that the organization 

 and the number of animalcules became elevated in direct pro- 

 portion to the mass of the body in a state of decomposition/' 



With a view to test this assertion, I took twelve test tubes 

 an inch in diameter and about three inches long, arranged in 

 two rows in a mahogany stand. By this means the extent of 

 surface exposed to the atmosphere would equal that of a good 

 sized vessel, and thus the chance of catching floating germs 

 would be considerable, while from the small dimensions of 

 each tube a fermentation of very limited extent could be con- 

 veniently carried on. 



The tubes were charged all alike, with about six drams of 

 distilled water, and exactly three grains of finely chopped new 

 hay in each. The whole set was placed on the mantelpiece of my 

 study, a room with a north aspect, and in which the summer 

 temperature remains tolerably steady. The experiment was 

 commenced on the 4th of July, and the tubes were examined 

 on the 17th of the same month, the thermometer having indi- 

 cated about 65° during the whole time. The hay had floated in 

 each vessel, and thus was favourably situated for atmospheric 

 influence, and in every case a mouldiness was noticeable. 

 Number 1 contained minute vorticellas, mostly without stalks, 

 the body when expanded being about 1 — 400". When con- 

 tracted these little creatures were lemon-shaped, the short- 

 neck being like the nipple-shaped projection noticeable on 

 that fruit. They were active and lively, showing alternate 

 contractions and expansions, and strong ciliary motion. No. 2 

 had a number of minute pear-shaped animalcules, with 

 conspicuous vacuoles at the thick end, and at the other a 

 narrowish neck ending in a small expanded tube. I do not 

 know exactly what they were, but their form was much like 

 that of the Sjpathidium hyalinum, drawn in Micrograjphic Die- 



