350^ Messrs. Pode and Laukester on the Development [June 19., 



of the tube to the boiling temperature, we, as a rule, completely submerged 

 our experimental tubes in boiling water for a period varying from five 

 minutes to half an hour. 3. The substances used in preparing the in- 

 fusions being necessarily of a very heterogeneous nature, we always 

 examined samples of the infusions before and after boiling, at the time of 

 closing the tubes, and were thus able to determine whether any change 

 had taken place in the visible particles contained in the fluid after a 

 lapse of time. 



The microscopes used by us throughout, working side by side with 

 samples from the same infusion, were a Hartnack's Stative VIII. ob- 

 jective No 10 a immersion, ocular 4, belonging to the anatomical depart- 

 ment of the University Museum, and a large Powell and Lealand belong- 

 ing to the Eadcliffie Trustees, which is provided with a y 1 ^ and a ^\ ob- 

 jective. The former of the two English glasses was more usually em- 

 ployed than the latter, on account of its greater convenience in manipu- 

 lation. 



Appearances in freshly prepared infusions. — Since the objects seen in 

 such infusions are remarkable, and have doubtless sometimes led to error 

 in subsequent examination of infusions, we may draw attention to them 

 now. In such freshly prepared infusions we have not unfrequently seen 

 appearances agreeing very closely with some of those figured by Dr. 

 Bastian in his book as coming into existence after boiling, sealing, and 

 preservation in a warm chamber. A freshly prepared and boiled strong 

 infusion of hay may present shreds of vegetable fibre, a considerable 

 number of dead Bacterium termo (some two or three to the field), 

 minute, highly refringent spherules, varying from the size of a blood- 

 corpuscle to the smallest size visible ; and such spherules are often 

 present in pairs, forming figure-of-8-shaped bodies, both smaller and 

 larger than Bacterium and of different optical character. Further, dumb- 

 bell-shaped bodies are not unfrequently to be observed of similar form 

 and size to Bacteria, but coarser in outline ; they dissolve on addition 

 of HC1, which Bacteria do not*. All these bodies exhibit constant 

 oscillatory (Brownian) movements. The addition of new cheese to 

 such an infusion (as shown by examination of a simple infusion of new 

 cheese taken by itself) adds a considerable number of highly refringent 

 spherules of various sizes (oil-globules) and finely granular flakes, also a 

 few Bacteria and (if the cheese be not quite new, almost certainly) fungus- 

 mycelium and conidia in quantity. 



Fresh-boiled turnip-infusion alone may contain so very few dead 

 Bacteria that none are detected with the microscope, or only one in a 

 drop. It presents a great number of minute, highly refringent spherules, 

 varying in size from 5 \ tf inch downwards, all in most active oscillatory 



* In the most carefully guarded of the experiments published by Dr. Child a few 

 years since in the ' Proceedings of the Eoyal Society,' a very small number of bodies 

 similar to these_were obtained ; and we suggest that they were of the same nature. 



