Development, &c., of Blood-vessels. By G. and F. E. Uoggan. 569 



The animal (by preference a house mouse) ought to be only 

 moderately well nourished, as both extremes of nutrition defeat our 

 object, either by obscuring the developing vessels by fat-cells, or 

 preventing the vessels from being formed. It ought first to be 

 gently anaesthetized by chloroform under a jar, and as soon as it is 

 insensible, it ought to be drenched with the anaesthetic, and then 

 left to die. We never lose time by injecting the animal and after- 

 wards allowing it to cool, as by that process not only do the cells 

 alter in shape, but the injection interposes an annoying obstacle to 

 vision when it has filled the vessels. 



As soon as it is dead, we open up the abdomen along the linea 

 alba, so as to completely expose the gravid uterus, and then seizing 

 the uterus of one side with fine pointed forceps, we raise it out of 

 the body cavity, so as gently to distend the membrane or broad 

 ligament which attaches it to the abdominal wall. On one side 

 of this membrane we place the smaller of a pair of the histological 

 rings invented by us, and already described in this Journal ; * and 

 without allowing it to glide or rub over the surface, we place the 

 larger of the two rings upon the smaller. In this way a miniature 

 tambomine is formed ; and after the two rings have been carefully 

 jammed one on the other, by a slight circular movement, the excess 

 of membrane can be snipped ofi" external to the rings, and a one- 

 half per cent, solution of silver in distiUed water poured upon 

 either or both surfaces, without preliminary washmg ; but after a 

 few minutes exposure to a dull light, the whole may be gently 

 washed with ordinary water. 



In our piece of membrane not only are the cells fixed in their 

 living shape, but, as the blood-vessels were full of blood when the 

 one ring was jammed upon the other, the distending blood was 

 thus retained within them, and the silver solution now fixes them 

 in this condition, and makes also the outlines of the cells, which 

 alone form them, distinctly visible. The membrane is now ready 

 for staining, the best of all methods for this purpose, according to 

 our experience, being the one invented and published by one of us. 

 By this method the membranous portion of the tambourine is first 

 soaked for a few minutes in methylated spirit, a teaspoonful in a 

 watch-glass or small saucer being suflicient. This is then pourtxl 

 away, and in its stead a few drops of a 2 per cent, solution of per- 

 chloride of iron in spirit is filtered upon the membrane. After a 

 few minutes a 2 per cent." sohition of pyroi^'allic acid in spirit is 

 next filtered upon it, and allowed to remain tlu're from a few 

 seconds to a few minutes, according to the depth of tint reipiireil, 

 and then the whole is well washed with ordinary water, and tho 

 staining process is complete. A few drops of glycerine may then 

 be phicecl u[)on tho membrane to clarify it, and the preparation 

 • Sec vol. ii. (I87'.i) !». W.u. 



