ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 927 



Harz, the discoverer of this fungus, places it in the Hyphomycetes, 

 a section of Gouidiomycetes ; but Karsten regards it as having 

 greater affinity with Entomophthora and Exobasidium. 



Rhizomyxa, a New Phycomycete.* — A. Borzi describes a new 

 parasitic fungus, found on the roots of a large number of herbaceous 

 plants, especially on those of Capsella bursa pastoris and Stellaria 

 media. The vegetative body of Bluzomyxa consists of a simple naked 

 Plasmodium, with scarcely differentiated parietal layer, and with from 

 10 to 30 small nuclei, granules of protoplasm, and vacuoles ; the Plas- 

 modium approximating very closely in form to that of the cell on 

 which it lies, even when this is an elongated root-hair. As soon as 

 the jjarasite has consumed the protoplasm of this cell, its reproduction 

 commences, which takes place in two ways, asexually by swarm-cells 

 and spores, sexually by fertilized oospores. 



The formation of swarm-spores takes place by the transformation 

 of the entire plasmodium into a zoosporangium. It contracts some- 

 what and invests itself with a thin wall of cellulose, the contents 

 become homogeneous and finely granular, and the vacuoles disappear. 

 The nuclei increase rapidly by division, and the whole of the proto- 

 plasm breaks up into a number of portions, which escape from the 

 zoosporangium and the nutrient cell, and become zoospores. The 

 escape is effected by means of a protuberance from the zoosporangium, 

 which pierces the wall of the adjoining cell. The zoospores are 

 spherical, with a short beak and one cilium, colourless, and contain 

 a small nucleus. Their motion is not affected by light, and lasts for 

 about a quarter of an hour. They then either perish, or, if in favourable 

 cii-cumstauces, perforate the wall of the cells of the root or of root- 

 Lairs ; they become invested with a thin cell-wall, out of which the 

 protoplasmic contents escape in the form of an amoeba into the cell of 

 the host ; and this myxamoeba then develoj)es into a new plasmodium. 

 This may then again produce zoospores or ordinary spores, which are 

 at first naked masses of protoplasm, but afterwards become invested 

 in a cell-wall. These spores may then either develope into small 

 zoosporangia containing only one or two swarm-spores, or their cell- wall 

 becomes very thick, and a mass of them hibernates within the host in 

 tLo form of a cystosorus, resembling that of Woronina polycyslis^ 

 Their further development was not observed. 



The sexual reproductive organs spring from plasmodia in no way 

 different from those that produce swarm-spores. The plasmodia destined 

 for this purpose become elongated and at length assume a club-sha})ed 

 form. This then divides by a wall of cellulose into two cells, a larger 

 spherical one, the oogonium, and a smaller oval one, the anthcridium, 

 which remain attached to one another ; both contain several nuclei. 

 The protoplasm of the oogonium now becomes differentiated into two 

 layers, separated by a thin membrane, the central denser one of which 

 is the oospherc, and alone takes part in the impregnation. The 

 anthcridium then puts out a cylindrical jirotuberance, which enters 



♦ Borzi, A., 'Illiizornyxa, nuovo Ficomicete,' 53 pp. (2 plb.) Messiua, 1884. 

 See Hot. CcutrallJ , xix. (1881) p. 1. 



