536 SUMMABY OP CURRENT RESEARCHES RELATING TO 



Formation of Spores of Gregarine of Earthworm.* — Dr. F. 



Henneguy has applied the section-method to the study of Gregarines. 

 The two chief difficulties met with are the small size of these creatures, 

 and the resistance offered by their investment to the penetration of 

 fixing liquids; these are best met by hardening the organisms in the 

 organs which contain them. Observations have been made on Clepsidrina 

 hlattarum, Klossia helicina, and Monocystis agilis ; but the last alone has 

 as yet given good results. 



If a series of sections of the so-called testicles of the earthworm are 

 made in May and June, almost all stages in the development of the 

 parasite may be observed. The young consist of a small mass of homo- 

 geneous protoplasm, which is surrounded by a delicate membrane, and 

 contains a nucleus of some size, which is provided with a nucleolus 

 which stains deeply with carmine. In the adult the protoplasm is filled 

 with refractive bodies ; these, when examined under a high power, are 

 seen to be rounded or ellipsoidal in form, and they may or may not be 

 of the same size. The author agrees with Maupas in regarding these 

 bodies as being amylaceous. From the characters which they present 

 with polarized light, it would seem that their axial portion consists of a 

 substance which is more condensed than the rest. 



The general results of previous observers on the development of 

 Monocystis are confirmed, and some new facts have been discovered as to 

 the part played by the nucleus. When a Gregarine is about to undergo 

 encystation the nucleus has a large nucleolus, and the surrounding 

 protoplasm is devoid of refractive bodies. Vacuoles soon appear in the 

 nucleolus, and this breaks up into several small grains of chromatin 

 which are connected by an achromatic plexus. The nucleus then under- 

 goes indirect division, and what appears to be an accessory nucleus is 

 developed. If the contents of the cyst do not divide, the nuclei continue 

 to multiply by karyokinesis and emigrate to the surface, where each 

 nucleus is soon surrounded by a small quantity of protoplasm. At the 

 moment when the peripheral layer of the cyst becomes organized into 

 cells one does not see around each nucleus the radiating lines which are 

 observed in the parablast of mesoblastic eggs when the nuclei become 

 the centres of cell-formation. It is very probable that the small size of 

 the cells of the cysts of Monocystis alone prevent us from seeing those 

 radiate lines which appear to play an important part in the formation of 

 the cellular plate. Each small superficial cell of the cyst soon becomes 

 surrounded by a resistant envelope, and becomes a spore or pseudo- 

 navicella. 



Some of the nuclei remain at the centre of the cyst and, later on, 

 undergo degeneration ; the process of their disappearance recalls that 

 which Flemming has noticed in the cells of the ovarian follicles of the 

 rabbit. When the contents of the cyst divide into a small number of 

 large masses the process of the formation of the spores is identical, and 

 each of these masses behaves like the undivided cyst. The method of 

 sporulation described by Lieberkuhn, in which the whole contents of 

 the cyst divide into spores, has not been observed by the author. Micro- 

 spores are formed in much the same way as macrospores. It is possible 

 that microspores and macrospores are not formed by one and the same 

 species. Both kinds contain a nucleus of some size, which is provided 



* Anu. de Microgr., i. (1888) pp. 97-107 (1 pi.). 



