303 



Lhiterbautdrüseu ualiezu ideutiscli". lu bis last publication bo- 

 wever be is of a different opiniou aud comes to tbe sarae results 

 as I did. Wbeu tbe fiue granular glands are treated witb 0,5 

 procent Na Cl solutiou duriug some time, tbe fine granules swell 

 and fuse togetber so as to form transparent globules , whicb 

 resemble oildrops (see fig. 16). 



In order to get an idea of tbe cbemical qualities of tbe 

 granules I bave takeu tbe following experiments. I dissected an 

 Hirudo mediciualis alive and prepared tbe glands on au object- 

 glass in 0,5 procent saltsolution. I tben placed a cover-glass on 

 tbe glands and removed tbe liquid partially witb blotting paper; 

 tbe weigbt of tbe coverglass was tben sufficiënt to empty tbe cells. 

 I uow was able to observe , bow tbe granules left tbe cells tbrougb 

 tbe ducts and accumulated at tbe opening of tbe secretory duet. 

 But not only after baving left tbe cells tbe granules swell and 

 fuse togetber in order to form globules , tbe same can be obtained 

 by laying tbe cells during some days in Na Cl solution ; tbe oil- 

 like globules are now situated in tbe cells. After some time tbese 

 globules , especially tbose near tbe orifices of several ducts, become 

 less refracting. 



Addiug very diluted acetic acid tbe globules become opaque , first 

 at tbe peripbery, but it advances slowly towards tbe centrum. 



Before bowever tbe centrum is reacbed , tbe globule beginns 

 to melt at its surface and soon tbe globule bas vanisbed too. 



Witbout addition of acetic acid and only by 0,5 procent salt- 

 solution tbe granules melt, but tbis takes some days and only 

 tbe nucleus is left in an irregular protoplasmatic network. 



Destilled water influences tbe granules but feebly and during 

 some bours no alteration is to be seen. 



Wben tbe granules are dissolved, tbe protoplasma retracts it- 

 self from tbe cellmembrane (see fig. 15), auotber time it is found 

 as a tbin layer along tbe cellmembraue. Diluted K O H makes 

 tbe granules swell very mucb, and even tbe membrane becoraes 

 gelatinous but soon all is transparent aud uotbing eau be di- 

 stinguisbed. 



