No. 3.] THE TAIL /A" LUMBRICULUS. 321 



In making preparations for the examination of the peritoneum 

 from its inner surface, the clearest views were obtained by stain- 

 ing with borax carmine and transferring to glycerine, at first 

 dilute and, finally, of nearly full strength. After a few days 

 the worms can be opened along any line desired, the alimentary 

 canal, etc., removed, and the body-wall opened out flat and 

 mounted in glycerine. Silver nitrate was used, but from the 

 extreme sensitiveness of Lumbriculus it was impossible to 

 stupefy the worms by the usual methods without their falling 

 to pieces, and silver nitrate upon preserved tissue, or from the 

 outside, did not yield entirely good results. 



In the case of Lumbricus, where the presence of earth in the 

 alimentary canal rendered it difficult, if not impossible, to get 

 an unbroken series of sections, the difficulty was obviated by 

 keeping the worms for several days in decayed stump earth 

 (humus), or in white or brown bread. The worms can easily 

 penetrate slices of bread moistened with water, and if the bread 

 is changed every day, no injurious fermentation occurs. These 

 two media were thought to offer less chance for pathological 

 change than the less nourishing diet of filter paper, which 

 answers to some extent for worms that are to be used almost 

 at once, and where there is no especial demand upon the sys- 

 tem, as is the case in regeneration. 



PART II. DESCRIPTIVE. 



The Lumbriculidae, as is well known, possess in a remarkable 

 degree the power to divide spontaneously and to reproduce the 

 extremity cast off or lost. In this respect they agree with the 

 Naids and some marine Annelids, but the regenerative process 

 of the latter forms differs in that zones of new tissue are devel- 

 oped before separation. 



After artificial division the regeneration in Lumbriculus seems 

 to be entirely normal. 



II. The General History of Division, whether artificial 

 or brought about by the worm itself, is as follows : Immediately 

 upon the separation of the worm into two parts, or perhaps 

 before the separation and consequent upon the stimulus that 

 causes it, a strong contraction of the muscles takes place. In 



