206 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Synchytrium. By culture experiments he was able to infect young- 

 tubers and watch the growth of the disease from stage to stage. The 

 resting spores or sporangia germinate in the early spring and produce a 

 large number of zoospores, which are oval or pear-shaped, with one 

 cilium ; these enter the young tissue of the buds on the thin rhizomes 

 and the " eyes " of the young tubers. In three or four days after infec- 

 tion, proliferation of the tissue begins, producing the warts. There is a 

 second form of sporangium produced in May and June, with thinner 

 walls and smaller zoospores, but otherwise similar to the resting sporangia. 



After entry into the host-cell, the parasite imbeds itself in the cyto- 

 plasm, and grows rapidly, soon being visible as a round thin-walled cell 

 with a central nucleus, and reticulated cytoplasm with denser portions of 

 irregular form. The nucleus contains a nucleolus, inside or around the 

 surface of which the chromatin is concentrated, and attached to it is a 

 peculiar and characteristic body of amoeboid form, which extends a short 

 distance into the nuclear cavity. At a later stage the reticulum breaks 

 up into swarm-spores. The development of the thin-walled sporangium 

 is also traced ; the cytoplasm of this cell is more dense than that of the 

 other ; the primary nucleus is large, and is frequently placed excentric- 

 ally ; a round nucleolus is also present, which becomes vacuolated when 

 the reproductive stage commences ; at the same time the nucleus shrinks 

 and disappears, the chromatin contained within it being found in the 

 form of " chromidia " in the cytoplasm of the parasite. Round the 

 chromidia small vacuoles appear, and nuclei arise at these points. The 

 primary nucleus was not seen to undergo recognisable mitotic division, 

 but undoubted mitosis was observed in the minute secondary nuclei. 



Percival gives his reasons, based on the life-history and development 

 of the organism, for placing it in the genus Synchytrium, and he further 

 suggests that the Synchytria, and possibly the majority of the Chytri- 

 diaceaj, may ultimately be placed among the Protozoa. 



Aspergillus glaucus.* — L. Mangin has studied this mould in order 

 to clear up the confusion as to the species included under that name. 

 He defines the species as having large globose or ovoid slightly warted 

 conidia (9-15 /x in diameter). Aspergillus repens, which has often been 

 united with the above, has much smaller conidia (7-8 ' 5 /a in diameter), 

 and also smaller ascospores. Mangin therefore divides the forms into 

 two groups : 1. A. glaucus, with large conidia and spores ; 2. A. repens, 

 including those with smaller conidia and spores ; but he also found that- 

 there was so much variation in the conidial form as regards size and 

 ornamentation of the conidia, due to temperature, etc., that it was not 

 possible to distinguish species by single conidia. Among the large 

 spored forms he recognises only one species, A. glaucus, but among the 

 smaller he differentiates A. Amstelodami sp. n., A. Chevaleri sp. n., 

 A. repens, and A. herhariorwn. Mangin gives a long account of his 

 cultures and of the observations made on temperature, coloration, etc. 



Study of Endomycetes.j — A. Guilliennond had undertaken a study 

 of this order of fungi to throw some light on the formation of the ascus 



* Ann. Sci. Nat., ser. 9, x. (1909) pp. 303-71 (15 figs.). 



t Rev. Gen. Bot., xxi. (1909) pp. 353-98, 401-19 (8 pis. and figs.). 



