PARTI.] Description of the ''Isolating Apparatus^ ii 



water 1 ounce. A drop of this was placed on three glass slides ; to these were 

 added : — 



No. I. — A minute quantity of the upper layer of intestinal contents. 



No. II. — A minute quantity of the sediment chiefly. 



No. III. — A minute quantity of diabetic urine containing " yeast-cells." 



These were placed as before under a bell-glass placed in Condy's fluid ; on the 

 third day specks appeared on the preparation in each slide, which proved to be due to 

 spores and mycelium (Plate IV, Fig. xvi), the three slides presenting similar appearances 

 under the microscope. On the fourth day No. I. presented an excellent forest of penicil- 

 lium, and No. II. a similar crop of aspergillus, of the black and purple coloured variety, 

 while No. III. produced both penicillium and aspergillus. These were systematically 

 examined for eight days, no other fungus making its appearance. The aspergillus 

 crop in No. II. presented tufts of different colours ; specks were observed in the 

 other two preparations ; a speck of yellow and brownish-purple being the most 

 abundant. 



To experiments conducted in this manner, there is the serious objection that 

 each time the preparation is examined, no matter how carefully, the possibility 

 exists of foreign matter getting into the preparation. With the intention of obviating 

 this source of fallacy as much as possible, an isolating apparatus, in the form of an 

 aspirator, was employed to supply the preparation with purified air, at least as pure 

 as passing it through concentrated sulphuric acid will allow. By referring to the 

 accompanying sketch it will be readily seen how this was effected (Plate V, Fig. xviii). 

 A small funnel (1) with a pledget of clean cotton wool inserted into its neck was 

 attached to a piece of bent glass-tubing ; this tubing passed through a perforation 

 in the cork of a flask (2) containing concentrated sulphuric acid ; from the neck of 

 this flask another piece of glass-tubing emerged which connected it with a perforated 

 bell-glass, standing in a shallow dish containing Condy's fluid; (3) another piece of 

 tubing connected this with the aspirator (4) filled with water. All the connections 

 were carefully luted, so that the only air which could have got at the preparation 

 on the stand within the bell-glass (of course minus the air which previously existed 

 therein) must have passed through the sulphuric acid. 



Illustration III. : — 



A perfectly fresh choleraic evacuation having been obtained two hours before 

 death (in a rapidly fatal case lasting only seven hours), three watch-glasses were 

 placed in the isolating apparatus with the following ingredients : — 



No. I. — A slice of the interior of a plantain weighing quarter of an ounce was 

 scooped out, and six drops of the sediment from the evacuation were placed in the 

 little cavity thus made. 



