1736 Journal of Applied Microscopy 



NOTES ON TECHNIQUE, III. 



On Injecting the Blood Vessels of the Earthworm. 



In specimens of the earthworm prepared for dissection by preservation in 

 alcohol, with or without previous treatment with chromic acid, the blood vessels 

 are always found to be contracted and shrunken and not showing the character- 

 istic color of the blood except in the largest vessels. Unless then an abundance 

 of live worms are at hand which can be used for the study of the vascular sys- 

 tem, class work on this particular subject is apt to be unsatisfactory. It is not 

 usually convenient to furnish living material in quantity for the study of the cir- 

 culatory system alone, and it has seemed highly desirable to make if possible 

 injected preparations of the blood vessels so that students would be able to 

 make out points which their own specimens did not show. After some experi- 

 menting on the subject it was found that good injections of the blood vessels of 

 the common earthworm could be obtained.- As the operation is in practice a 

 rather difficult one, and since in the experience of the author it is impossible to 

 attain successful results by the use of the ordinary injection methods, it seems 

 advisable to publish an account of the procedure employed. 



Fig. 1. — Showing form of the glass tube used for injection in place of syringe. About 



one-half natural size. 



The main difficulties encountered were of two different sorts : (a) the small- 

 ness of the vessels made the introduction of the cannula very difficult, and (b) 

 the walls of the vessels were so thin that they would withstand only the gentlest 

 and steadiest of pressure. All attempts to inject by means of a syringe (hypo- 

 dermic or larger) were unsuccessful. Furthermore, none of the masses ordina- 

 rily used for macroscopic injection nor any of several of the masses advocated 

 for microscopic work were found to be adapted to this work. Either the mass 

 would not run in the vessels or else it would cause them to burst, or finally it 

 would not " set " after filling the vessels. 



It was finally found best to use a bent glass tube drawn to a fine point at one 

 end (Fig. 1) in place of a syringe. By blowing at the upper end of such a tube 

 partially filled with injection mass it was found that a much steadier and more 

 easily regulated pressure could be obtained than with any syringe. Furthermore, 

 the tube could be better inserted into the vessels and held more steadily after 



1 Tandler, J. Mikroskopische Injectionen mit kaltfliissiger Gelatin. Zeitschr. f. wiss. 

 Mik. 18: 22-24, 1901. Reviewed in this journal, 5 : 1625 and 1626. 



It was found necessary to use a slightly larger amount of KI than is recommended by 

 Tandler in order to keep the gelatine fluid until after injection. Eight to ten grams of the KI to 

 100 c. c. of fluid were used. 



