ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 509 



with the subject was referred to, and some useful hints were given for 

 the collection and cultivation of these interesting organisms. The 

 lecture was illustrated by a series of coloured drawings and a large 

 number of preparations of Mycetozoa under Microscopes. Mr. J. Burton 

 showed some active swarm-cells of Brefeldia maxima. 



B. Technique.* 

 (1) Collecting- Objects, including:] Culture Processes. 



Cultivating and Preparing Hypotrichous Infusoria.f — L. L. Wood- 

 ruff cultivated these organisms on slides, having a central circular con- 

 cavity with a capacity of about 5 drops of water. Cover-glasses were 

 not employed. The slides were kept in moist chambers to prevent 

 evaporation of the preparations. These were dishes about 10 in. in 

 diameter and 3 in. deep. In the bottom of the dish was placed about 

 2 in. of wet sand. Over the sand was placed a glass plate, on which 

 rested 4 parallel strips of glass, and on these the slides with the Pro- 

 tozoa were arranged. The whole was covered with a ground-glass top. 

 The Infusoria were handled with a pipette drawn out to a fine point ; 

 each pipette was used for one purpose, and one only. For detecting 

 the Infusoria, a simple lens with a magnification of about ten diameters 

 was used. 



The culture medium was made from infusions of hay or fresh grass, 

 and was prepared as follows : — about 3 grin, of grass or hay were washed 

 in tap-water, and then placed in a beaker containing about 200 c.cm. of 

 tap-water. This was boiled for 1 minute. In most cases the infusion 

 was used shortly after it had cooled, but occasionally was allowed to 

 stand for 24 hours. 



One individual from each line of the culture was removed daily, in 

 order to prevent the possibility of endogamous conjugation. The maxi- 

 mum and minimum temperatures of the laboratory in the vicinity of the 

 culture were recorded daily. 



For the purpose of following the changes in cell-structure during 

 the life of the cultures, permanent preparations were made from time 

 to time. The specimen to be preserved was isolated by means of a 

 pipette, and deposited on a slide, and then 3 or 4 drops of a saturated 

 solution of sublimate with 5 p.c. acetic acid added. After about 5 

 minutes the specimen was transferred to another slide, and a few drops 

 of 75 p.c. alcohol deposited thereon. The specimen was next removed 

 to a third slide already smeared with egg albumen. When the albumen 

 has coagulated and fixed the specimen, the slide is transferred to agar 

 of 75 p.c. alcohol, and afterwards treated by ordinary methods. 



For staining, Ranvier's picrocarmin was used, though Delafield's 



* This subdivision contains (1) Collecting Objects, including Culture Pro- 

 cesses ; (2) Preparing Objects ; (3) Cutting, including Imbedding and Microtomes ; 

 (4) Staining and Injecting ; (5) Mounting, including slides, preservative fluids, etc. ; 

 (6) Miscellaneous. 



t Journ. Exper. Zool., ii. (1905) pp. 585-632 (3 pis.). 



