442 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
B. Technique.* 
(1) Collecting- Objects, including- Culture Processes. 
New Observation Media, j* — M. J. Amann recommends the following 
media as suitable for clarifying and observation purposes. 
(1) Chloralphenol is prepared by mixing 2 parts of chloral hydrate 
and 1 part of pure phenol. This makes an oily fluid, which begins 
to crystallise at 10° C. The refractive index is 1*5241. It possesses 
good clearing properties, and delicate histological elements are little, if 
at all, contracted. For the fixation and rapid demonstration of nuclei, 
e.g. Oscillaiorise, it is especially useful. It is an excellent dehydrant,, 
and the technique is simple. The living object placed on a slide when 
treated with chloral phenol is simultaneously killed, fixed, cleared up,, 
and dehydrated. The first quantity should be poured off, and replaced 
by another. If the specimen be thick or stained or woody, the medium 
may be heated, and then replaced by balsam added drop by drop. 
(2) Chlorallaclophenol is composed of 2 parts by weight of chloral 
hydrate, 1 part of pure phenol, and 1 part of lactic acid (sp. gr. 1*21).. 
This is an oily fluid miscible with water. In all proportions N D = 1 *4932. 
It clarifies well, and is especially suited for herbarium material, to which 
it restores the original form. The refractive index can be raised by the 
addition of salicylate of soda : chloral hydrate 4 parts, phenol 4 parts,, 
lactic acid (sp. gr. 1*21) 2 parts, salicylate of soda 1 part. 
(3) Lactochloral is a mixture of equal parts of chloral hydrate and 
lactic acid ; N D = 1*4796. It clears up well, and can be used for dry 
material. 
(4) Chlor phenol, p-monochlorphenol (4-1), has a refractive index 
of 1*5671. It clears up vegetable preparations very strongly, the cell- 
membrane becoming almost invisible. It is extremely valuable for 
observing the polarisation picture of organic preparations. It is an 
excellent dehydrant, does not contract delicate tissues, does not cause- 
the cell-wall to swell up, nor does it affect the colour of chlorophyll. 
(5) Chloralchlor phenol is a mixture of equal parts of chloral hydrate 
and p-monochlorphenol. It is a thick oily fluid miscible with v\ater y 
and has a refractive index of 1*5491. It possesses, though in a higher 
degree, the same properties as chlorphenol. 
(6) Lacioehlor phenol is composed cf 1 pait of lactic acid and 2 parts- 
of jp-monochlorphenol. Its refractive index is 1*5265. 
(7) Chl( rallactochlorphenol is composed of equal parts of p-mono- 
chlorphenol, chloral hydrale, and lactic acid. The refj active index is 
1*4995. Preparations treated with this medium, and intended to be 
mounted in 1 alsam, must be dehydrated with chloralchlorphenol. 
(8) Copper media. In order better to. retain the green colour of 
preparations, a saturated solution of copper chloride in the proportion of 
two per thousand may be added to any of the foregoing media. 
(9) Chinolin has a refractive index of 1*6218, and is very suitable- 
for diatom preparations. 
* 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, &c. ; 
{6) Miscellaneous. f Zeitschr. f. wiss. Mikr., xvi. (1809) j p. 38-44, 
