1664 Journal of Applied Microscopy 



CYTOLOGY, EMBRYOLOGY, 



AND 



MICROSCOPICAL METHODS. 



AGNES M. CLAYPOLE, Throop Polytechnic Institute. 



Separates of Papers and Books on Animal Biology should be sent for Review to Agnes M. Claypole, 



55 S. Marengo Avenue, Pasadena, Cal. 



Heidenhain, M. Ueber eine Paraffineinbettung The advantages of this process are as 

 mit Schwefelkohlenstoff als Durchgangs- follows : (1) Carbon-bisulphid is an ex- 



medium. Zeit. f. wiss. Mikros. u. f. mikros. ^ , , , r , 



Tech. 18: 166-170,1901. tremely good penetrator, a fact prob- 



ably dependent on its low molecular 

 weight in comparison with that of the aetherial oils usually employed. (2) The 

 greater number of the embedding processes can be carried on at the low 

 temperatures of 41°-42° C; since at this temperature carbon-bisulphid holds a 

 great deal of paraffin in solution. (3) This low temperature makes it possible 

 to leave the tissue in the mixture longer without injury, thus also ensuring 

 better embedding. (4) Carbon-bisulphid does not cause oxidation, hence easily 

 oxidizible stains, as chromhematoxylin, can be used before infiltration. 



Three bottles of mixtures are used, one of carbon-bisulphid and alcohol in 

 equal parts ; a second and third, of the liquid pure. Tissues after complete 

 dehydration are left in each bottle for "24 hours. Well stoppered bottles are 

 kept at the temperatures of 86°-3S° and 56°-,57°, respectively, and paraffin 

 added to saturation ; in case of using the higher temperature, 3-4 volumes of 

 paraffin go into solution. But very much goes in at the lower, which is below 

 body heat. After the tissues have been in both mixtures, they are put into 

 pure paraffin at 55°. They are passed through two separate vessels for an 

 hour each, to certainly remove all trace of carbon-bisulphid. 



Pieces of tissue thus treated are glassy, transparent, honey-colored, and 

 homogeneous ; moreover, they cut extremely well. Even muscle cuts in sections 

 of 4 yw in thickness with no trace of " knife artefacts." There are a few 

 precautions to be taken in the use of this reagent. First, it is highly inflam- 

 mable, and only closely fitting, ground-glass stoppered bottles should be used. 

 None of the bottles containing either the sulphid, or the mixture of it and 

 paraffin should be opened near a flame. Second, to avoid the extremely dis- 

 agreeable smell. Experiments proved that this can be almost entirely avoided 

 by keeping the liquid as undisturbed as possible ; shaking a vessel containing 

 it may easily be followed by an explosion of carbon-bisulphid gas. Vessels 

 should always be lifted carefully, pieces of tissue should be put in gently, and 

 the generation of gas is largely avoided. 



After the tissues have been in the paraffin mixture for some time, the whole 

 should be stirred by shaking moderately ; but obvious precautions can be taken 

 to avoid dangerous or unpleasant results. While the pieces of tissue are in the 

 carbon-bisulphid-alcohol mixture they are transparent. Passing into pure car- 

 bon-bisulphid produces some clouding. At first the pieces float, but with 

 saturation sink to the bottom. 



