June 26, 1903.] 



SCIENCE. 



1007 



method of introducing bibliography into text- 

 books. Joseph McFarland. 

 Medical and Chieurgical College, 

 Philadelphia, Pa. 



SOCIETIES AND ACADEMIES. 



academy of science of ST. LOUIS. 



At the meeting of June 1, 1903, Drs. B. M. 

 Bolton and D. L. Harris exhibited sections 

 cut after infiltration with agar-agar, and de- 

 scribed the use of this material for embedding 

 purposes as follows : 



Tissues can be readily hardened and em- 

 bedded for cutting into sections in a hot solu- 

 tion of agar-agar containing formalin. The 

 proportions of the mixture which have so far 

 yielded the best results are nine parts of a 

 five per cent, aqueous solution of agar-agar 

 to one part formalin. This mixture can be 

 prepared beforehand and kept indefinitely in 

 an air-tight vessel. The agar-agar should be 

 boiled for several hours, and after the addi- 

 tion of the formalin allowed to clear by sedi- 

 mentation. The bits of tissue to be embedded 

 are placed in a wide test-tube or wide-mouth 

 vial containing the mixture previously melted. 

 This is kept at 65-70° C. for an hour or 

 longer, and the tissues are ready to be blocked. 

 After attaching to blocks they are placed in 

 strong or absolute alcohol for an hour or two 

 and can then be cut. It is important not to 

 use dilute alcohol. The tissues are stuck to 

 the blocks by means of the agar-agar itself 

 and adhere as soon as the agar becomes cold. 

 No previous hardening of the tissues is at all 

 necessary; fresh tissues can be placed at once 

 into the hot agar-agar-formalin mixture; in 

 fact, fresh tissue is more desirable than that 

 which has been previously hardened, though 

 this can also be readily embedded by this 

 method. But the main advantage of the 

 method, aside from its convenience and sim- 

 plicity, is the fact that the cells of the tissues 

 are not at all contracted or shrunken, and the 

 ordinary methods of hardening have this effect 

 more or less. With sections prepared from 

 fresh tissues by this method the cell-proto- 

 plasm fills out the membrane fully, and the 

 granules of the protoplasm, the nuclei, and the 

 cell contours are remarkably distinct. The 



whole process, hardening, embedding and cut- 

 ting, does not occupy more, than three or four 

 hours, where the tissues are not larger than 

 about one centimeter in diameter. 



Professor A. W. Greely presented the re- 

 sults of an investigation of the relations of 

 ParamoBcia and other protozoa to chemical and 

 electrical stimuli. A detailed account of this 

 investigation has been contributed to Science. 

 Wm. Teelease, 

 Recording Secretary. 



THE geological society of WASHINGTON. 



At the 143d meeting of the society, held in 

 the assembly hall of the Cosmos Club, 

 Wednesday evening, April 22, 1903, a general 

 discussion on the problem of the occurrence 

 and storage of crude petroleum and petroleum 

 products was opened by Dr. David T. Day in 

 a paper entitled ' Experiments on the Dif- 

 fusion of Crude Petroleum through Puller's 

 Earth.' 



Dr. Day reviewed a series of experiments 

 which he has been carrying on intermittently 

 within the last five years on the changes which 

 take place in crude oils by diffusion through 

 various porous substances. 



It was found that if crude petroleum were 

 allowed to pass slowly through finely pulver- 

 ized fuller's earth, it became separated by 

 fractional diifusion into a series of oils differ- 

 ing in color and specific gravity from the 

 original product, and representing the com- 

 paratively simple oils of which the complex 

 crude petroleum is composed. In color the 

 fractions varied from the dark brown or am- 

 ber of the crude to the clear white of refined 

 petroleum, and variations in specific gravity 

 from .70 to .85 were secured. 



An account was given of a series of experi- 

 ments conducted by Professor Engler, to de- 

 termine the nature of the changes which took 

 place in the oil. Professor Engler's conclusion 

 was that no chemical change whatever took 

 place in the process of diffusion, the differ- 

 ences in the resulting products being entirely 

 physical. 



Experiments as to the effectiveness of vari- 

 ous diffusion media tended to prove that the 

 best results are invariably attained by the use 



