LOEFFLER'S ALKALINE 



140 



LYMPHATIC VESSELS 



emended Soc. Am. Bact. A. Methylene 

 blue (90% dye content) 0.3 gm. + 95% 

 ethyl alcohol, 30 cc. B. 0.01% aq. KOH 

 by weight 100 cc. Mix A and B 

 (McClung, p. 137). 



Logwood. This source of hematoxylin, the 

 most important of the older dyes, was 

 discovered by the Spaniards at the 

 Bay of Campeachy in Mexico and was 

 introduced by them into Europe. 

 Much used in Spain in the IGth centurj^ 

 logwood was banned in England i3y Act 

 of Parliament in 1589 and punishment 

 provided for its use. A hundred years 

 later this Act was repealed and since 

 1715 the tree has been cultivated in 

 Jamaica (Leggett, W. F., Ancient and 

 Medieval Dyes. Brooklyn: Chendcal 

 Publishing Co., Inc., 1944, 95 pp.). 



Loose Connective Tissue. Subcutaneous 

 tissue of this sort is often chosen for 

 investigation. It may be dissected out 

 and spread on slides. A good way, 

 demanding practice, is to tease the tis- 

 sue apart, without the addition of any 

 saline solution, so that one edge is paral- 

 lel to the end of the slide and about 4 

 cm. from it. This edge is allowed to 

 dry and become affixed to the slide, 

 while the remainder of the tissue is 

 kept moist and is stretched with needles 

 evenly along the length of the slide into 

 a fairly thin film. This spread is then 

 examined in the fresh state, with various 

 solutions added, or it is fixed and stained 

 like a blood smear. Separation of 

 components into a sufficiently thin 

 spread is facilitated by first making a 

 bulla (L. for bubble) under the epi- 

 dermis bj' the local injection of fluid 

 (salt solution, serum, etc.). 



Sylvia H. Bensley (Anat. Rec, 1934, 

 60, 93-109) employed a graphic method 

 for demonstration of ground substance. 

 She adapted a culture of paramoecia to 

 0.6-0.8% salt solution, injected sub- 

 cutaneously into a guinea pig, excised 

 the bulla and examined it as a whole 

 mount with cover glass supported at 

 edges. Actively motile organisms sud- 

 denly rebounded without coming into 

 contact with microscopically visible 

 structure and none escaped into the 

 surrounding fluid from the bulla. This 

 is evidence of the existence in loose 

 connective tissue of an amorphous 

 ground substance in the physical condi- 

 tion of a gel. She described, and used 

 to advantage, methods for determina- 

 tion of the refractive index, consistency, 

 digestability and tinctorial properties 

 of this substance in several parts of the 

 body. 



Methods for the identification of 

 CoUagenic and Elastic Fibers, Fibro- 

 blasts, Tissue Basophiles and other 



constituents are described under the 

 respective headings. See also Tissue 

 Fluid. 



Lorrain Smith, see Nile Blue Sulphate. 



Lubarsch Crystals are tiny formations occa- 

 sionally seen post-mortem intracellu- 

 larily in testis and said to be different 

 from Charcot's and Spermin Crystals. 



Lucidol, a trade name for benzoyl peroxide. 



Lucite, disadvantages of as substitute for 

 Canada balsam (Richards, 0. W. and 

 Smjth, J. A., Science, 1938, 87, 374). 

 It is used in place of Quartz for transil- 

 lumination by Williams, R. G., Anat. 

 Rec, 1941, 79, 263-270, and in making 

 containers for museum specimens by 

 Snitman, M. F., Arch. Otolaryng., 

 1942, 36, 220-225. 



Lugol's Iodine. Potassium iodide, 6 gm.; 

 iodine, 4 gm.; aq. dest., 100 cc. 



Luminoi (3-aminophthalhydrazide) made 

 by Eastman Kodak Co. has a marked 

 affinity for hematin yielding brilliant 

 luminescence in ultraviolet light. 

 Hematin in a dilution of 1:100,000,000 

 can be detected thereby. This is a 

 medicological test of great sensitivity 

 but is not limited to human blood 

 (Proescher, F. and Moody, A. M., J. 

 Lab. & Clin. Med., 1938-39, 24, 1183- 

 1189). 



Lungs. To excise properly pieces for fixa- 

 tion requires great skill especially if 

 lesions are present. The slices should 

 be cut with the sweep of a particularly 

 sharp knife to minimize squeezing and 

 the resultant distortion and displace- 

 ment of fluids when these are present. 

 The contents of small cavities and 

 bronchi may escape unless care is taken 

 to retain them by immediate coagula- 

 tion by fixation. Owing to regional 

 differences it is important to select 

 representative areas. To demonstrate 

 the fibrin often present in lesions, 

 Weigert's stain is recommended. 



Observation of lung through thoracic 

 window in vivo (Terry, R. J., Science, 

 1939, 90, 43-44), see Celluloid Corrosion 

 preparations. Alveolar Pores. 



Lutecium, see Atomic Weights. 



Lymphatic Vessels. There are many ways 

 of demonstrating lymphatic vessels. 

 The most convenient is to sit in an easy 

 chair and view the splendid moving 

 picture prepared by Dr. Richard L. 

 Webb of the Department of Anatomy of 

 the University of Illinois College of 

 Medicine entitled: "Mesenteric lym- 

 phatics, their conduct and the behavior 

 of their valves in the living rat". 



Another easy method is to watch 

 absorption of cream in a cat. A fasting 

 animal is fed | pint of cream and the 

 abdominal cavity is opened under ether 

 anesthesia a few minutes later. At first 



