BIHANG TILL K. SV. VET.- AKAD, HANDL. BAND 27. AFD. IV. N:0 6. 31 



testes and ovaria of Nephelis, Aulostomum and Hirudo, and 

 that they attack tbe spermatoblastes and the ova with the 

 result that these flnally become absorbed. In addition, he 

 also states that ripe eggs in the Hirudinids are destroyed by 

 a fatty process of degeneration. 



Considering that there are mainly two kinds of plasma- 

 cells which seem to partake in the resorption-process in Meso- 

 thuria intestinalis, it may be suitable to first give an account of 

 them. This description refers only to cells and tissues 

 which have been fixed and hardened in a mixture of formaline 

 and bichromate, or in a sublimate-solution. The staining is 

 regularly performed in iron-hciematoxyline according to the 

 method of Haidenhain, with or without after-dyeing in acid 

 fachsine or other aniline-solutions. 



1. Wander-cells with vacuoles are oval or irregularly rounded 

 large cells with a deeply stained nucleiis, and are distin- 

 guished by the extreme vacnolation of their clear protoplasm. 

 In preparations treated with iron-hsematoxyline, the circum- 

 lerence of the larger and smaller vacuoles has acquired an 

 almost black colour, the protoplasm presenting a reticular, 

 somewhat knotted aspect. The plasm separating the vacuoles 

 is clear and finely granulated. It is evident that these plasma- 

 cells exhibit great variations in general appearance, the va- 

 cuoles themselves being capable of changing in size and number. 

 In a living state, the cells in question may protrude pseudo- 

 podia in all directions. Cells are not seldom met with. in 

 which the reticular aspect has disappeared, whereby the clear 

 protoplasm of the cells seems to enclose a number of dark 

 coloured V-shaped loops. It may be left undecided whether 

 this is due only to an incompleteness in the staining process, 

 or whether we have to do with another kind of plasma-cells. 

 The cells with vacuoles are distributed in all tissues, but par- 

 ticularly in the connective tissue. 



2. Cells icith spheres are the second kind of migratory 

 cells which exhibit a totally differeut appearance. They are 

 considerably larger than the former and are frequently much 

 elongated, though there are to be found all transitional forms 

 between globular ones and elongated cells. They present 

 themselves under several different aspects this being evidently 

 due to different stages in the development. Thus, for instance, 

 bodies occur containing, besides a spherical nucleus, an abun- 



