776 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the study of fossils by serial thin sections, may be obviated by means 

 of serial polished surfaces obtained at any desired degree of proximity* 

 and these when the fossil and its matrix offer sufficient optical contrast,, 

 serve most of the purposes of thin slices. They may be photographed 

 under the Microscope so as to furnish a trustworthy and permanent 

 record. The sections, which are obtained at intervals of about 0*025 

 mm., may be also used for reconstructing the fossil in wax. 



Application of the Cinematograph Principle to the Study of 

 Serial Sections.— B. E. Kelly.* The tissue is fixed, stained in bulk 

 and imbedded in paraffin. The most convenient width of the paraffin 

 block was found to be three-eighths of an inch. A ribbon is cut, floated 

 on to warm water, and then stuck on to a celluloid film by means of an 

 albuminate fixative. When dry, the paraffin is dissolved in xylol, and 

 the sections are fixed to the film by means of a varnish. A French oil- 

 varnish has been hitherto used. When thoroughly dry, the film is rolled 

 up and placed in a cinematograph apparatus, and the sections are 

 projected on a screen by means of a camera ; or the working portion of the 

 cinematograph camera is placed on the stage of a microscopic projection 

 apparatus, or even on the stage of an ordinary Microscope. The 

 advantages claimed by this method are : 



1. The ease with which a series of sections can be demonstrated to 

 an audience. 



2. The unique impression of continuity. 



Simple Method of Making Collodion Sacs for Bacteriological 

 Work.f — W. D. Frost uses small test-tubes for this purpose. Thick 

 collodion is poured into the tube to a depth equal to the desired length 

 of the sac. It is then poured out along one side of the tube into- 

 another, and then again' into another in the same way. The coated 

 tubes are then placed mouth downwards in a rack to drain off excess 

 and to dry. When dry, the sac usually shrinks and may be easily pulled 

 out. The sacs may be kept a long time in water. To sterilise the sac 

 it is three parts filled with bouillon or other medium, and immersed in a 

 tube of the medium. The sac is held in position in the tube by means 

 of the tongue formed by the collodion flowing out of the tube. Before 

 the sac is put in the tube, a piece of cotton or silk is placed round its 

 upper part and loosely knotted, the ends being taken outside the tube. 

 Sterilisation is then effected in the usual way. The medium in the sac- 

 is then inoculated with a platinum needle, and the tube incubated for 

 24 hours. If at the end of this time the medium outside the sac be 

 clear, the integrity of the latter may be accepted. The sac is then 

 pulled out and the cotton or silk drawn tight and tied, and the ends cut 

 off along with the ends of the sac. The mouth is finally sealed with 

 collodion. The sac is then ready for introduction into the body cavity 

 of an animal. 



The advantages claimed are : (1) Simplicity ; (2) No danger from 

 air bubbles ; (3) May be made of any size or shape ; (4) No glass to- 

 break or irritate the animal ; (5) Maximum amount of dialysinir 

 surface. 



* Brit. Med. Journ., ii. (1903) pp. 313-4. 



+ Centralhl. Bakt. l te Abt. Orig., xxiv. (1903) pp. 733-5. 



