ZOOLOGY A.XD BOTANY, MICROSCOPY. ETC, 



37a 



On warmiiio- above a certain temperature, the expansion of the ether 

 vapour presses up a cohunn of mercury against and closes the end of the 

 tube d, whereby the stream of cold water is able to pass by the opening e 

 into the npper tank ; on cooling the mercury recedes, the tube d is 

 opened, and and the water passes to a waste outside the tank. In order 

 that the temperature of the lower reservoir may be lowered as quickly 

 as possiljle, a tube passes from the cool tank through the lower warm 

 tank, and as soon as the mercury column 

 allows the cool water to enter the apparatus, 

 the cool water passing through this tube 

 from the upper tank will cool the lower 

 warm tank l)efore it leaves the apparatus 

 by the outflow. 



Cultivation and Preservation of My- 

 cetozoa. — Microscopiists interested in 

 Mycetozoa often experience difficulty in ob- 

 taining specimens for study and preservation. 

 Much time may be lost in looking for them, 

 even at suitable seasons and in likely places. 

 A. E. Hilton finds that this difficulty may 

 be partially overcome by taking short pieces 

 of branches, say about S in. long by 1*5 in. 

 in diameter, keeping them moist, and ex- 

 amining them twice or thrice a week. In 

 the course of ten days or a fortnight spor- 

 angia usually appear, occasionally in con- 

 siderable numbers. Specimens of Arcyria, 

 Gomatrkha, BrefeJdia, and other genera 

 have been obtained in this way. Branches 

 found in Highgate Woods, treated in this 

 manner, generally produce Comatricha ohtu- 

 sata. Pieces recently broken off, and partly 

 covered with bark, give best results. The 

 simplest method of keeping them moist is 



to take some ordinary glass jars, such as pounds of preserves are sold in ; 

 stand the pieces of branches on end, one in each jar ; pour in water to the 

 depth of an inch, and replenish from time to time as necessary. Another 

 way is to take some shallow baking tins ; cover the bottoms with 

 " felting," or other fibrous material which will retain moisture ; keep 

 wet by adding water as often as requisite, and lay the pieces of wood 

 side by side. Spring and autumn are the most favourable seasons for 

 Mycetozoa, as cold, hot, or dry weather does not suit them. 



Plasmodia of Badlumiia utrmdaris can be cultivated from sclerotia, 

 by moistening the latter in a dish along with fragments of fungi, either 

 Stereum hirsutum or Auricularia mesenterica. A little water must be 

 added occasionally, and a sheet of glass should be placed so as nearly to 

 cover the dish and prevent too rapid evaporation. Plasmodia grow 

 more rapidly on Stereum than on Auricidaria ; but care has to be taken 

 to remove the pieces of Stereum when the plasmodia have passed over 

 them, otherwise they are apt to putrefy, and may kill the plasmodia. 



Fig. G4. 



