872 SUMMARY OF CURRENT RESEARCHES RELATING TO 



eight hours. They arc next thoroughly soaked for three or four days 

 and the gland-cells isolated by teasing in distilled water or in 

 glycerin and water (equal parts), llrcrnatoxylin or Ecnaut's hajma- 

 toxylin-glycerin arc the best stains. 



4. Flemming's mixture. — Pieces of tissue are left for not longer 

 than twenty-four hours in the mixture and afterwards soaked for 

 several days and then hardened up to dehydration in alcohol, im- 

 bedded in celloidin, and stained as before. 



5. Alcohol. — 70 to 90 per cent, alcohol may be used for pieces of 

 limited size ; the various structures are well preserved, and staining 

 is almost always successful. 



Preparing Striated Muscular Fibres.* — Dr. A. Eollett places 

 small pieces of muscle just removed from the living animal in albumen 

 of a fresh-laid hen's egg, and then cuts them in a freezing microtome 

 (Jung's). A well-tempered knife is necessary. The still frozen 

 section is placed on a slide, and can be examined at once with the 

 albumen still adhering to it, or the latter may be replaced by a mixture 

 of two parts glycerin and one part water. The sections are trans- 

 parent and uncrumpled. Crumpling occurs when sections of frozen 

 muscle are produced without the aid of albumen. 



A similar procedure can be applied to the muscle of beetles which 

 have lain only a short time in alcohol. The sections are put straight 

 into glycerin. Muscles hardened for a longer time in alcohol are 

 cut in celloidin. The objects are laid for twenty-four or forty-eight 

 hours in a thin solution of celloidin, and then placed for twenty-four 

 hours in a celloidin solution composed as follows : — Celloidin, 1 grm. ; 

 mixture of ether and alcohol in equal volumes, 4 c.cm. 



The object immersed in this solution is then placed in a small 

 covered vessel until the celloidin has, through slow evaporation of its 

 solvents, assumed a jelly-like consistence. The mass is then cut all 

 round and turned on to a glass plate, then reversed and put back in the 

 glass vessel, some fresh solution is poured over, and the object sinks 

 down in the midst. When taken out of the jelly-mass it is hardened 

 in a mixture of 93 per cent, alcohol two parts and water one part, 

 for twenty-four hours, staining with a weak solution of Renaut's 

 hematoxylin, then alcohol, origanum oil, and dammar resin in xylol. 



Isolating the Epidermis of Human and other Embryos from the 

 Dermis.f — Dr. C. S. Minot describes a method for this purpose which 

 is also convenient for the study of the development of hairs. 



It is well known that if the foetus dies and is retained, it is 

 preserved for a considerable period without disintegration of the 

 tissues in the amniotic fluid. In specimens thus preserved it is often 

 found that the epidermis is loosened so much that strips can be 

 removed without tearing off the underlying tissues. Now, as the 

 amniotic fluid is little more than a salt solution, the facts just stated 

 naturally suggest that a salt solution preserved from septic changes 



* Denksehr. Math.-Naturw. Kl. K. Akad. Wiss. Wien, li. (.1885) 48 pp. and 

 4 pis. Cf. Zcitscbr. f. Wiss. Mikr., iii. (1886; pp. 92-3. 

 t Amer. Natural., xx. (1886) p. 575. 



