120 Experiments on the Development of 



Lealand belonging to the Kadcliffe Trustees, which is provided with 

 a TVth and a gVth objective. The former of the two EngHsh glasses 

 was more usually employed than the latter, on account of its greater 

 convenience in manipulation. 



Ap2^earances m 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 

 iermo (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, dumbbell-shaped bodies 

 are not unfrequently to be observed of similar form and size to 

 Bacteria, but coarser in outline ; they dissolve on addition of HCl, 

 which Bacteria do not.* All these bodies exhibit constant oscil- 

 latory (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 re- 

 fringent 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^oW ^^^^ downwards, all in most 

 active oscillatory movement. Shreds and filaments of various sizes 

 and character also are found, and a few finely granular flakes about 

 T-fij^ inch in diameter. The addition of cheese brings in, of course, 

 the objects enumerated above as belonging to it. 



Visihility of Bacteria. — It is perhaps necessary to say, before 

 proceeding further, that we have satisfied ourselves that, in in- 

 fusions of the optical character of those used, the multiplication of 

 Bacteria makes itself obvious by a cloudiness. Hence, though we 

 have not remained content with that evidence, the retention by 

 such a hmpid infusion of its limpidity is a proof of the absence 

 of Bacteria. We also should mention, what is well known already, 



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

 a few years since in the ' Proceedings of the Royal Society,' a very small 

 number of bodies similar to these were obtained ; and we suggest that they were 

 of the same nature. 



